For now, instead of reaching for a designer supplement, you're better off taking a multivitamin, according to some experts. It's well known that antioxidants like vitamins C and E protect cells from damage by disarming free radicals. Brain cells are especially vulnerable to these troublemakers because the brain generates more free radicals per gram of tissue than any other organ. Antioxidants also protect neurons by keeping blood vessels supple and open, ensuring the flow of nutrients to the brain.
Your mileage will vary. There are so many parameters and interactions in the brain that any of them could be the bottleneck or responsible pathway, and one could fall prey to the common U-shaped dose-response curve (eg. Yerkes-Dodson law; see also Chemistry of the adaptive mind & de Jongh et al 2007) which may imply that the smartest are those who benefit least23 but ultimately they all cash out in a very few subjective assessments like energetic or motivated, with even apparently precise descriptions like working memory or verbal fluency not telling you much about what the nootropic actually did. It’s tempting to list the nootropics that worked for you and tell everyone to go use them, but that is merely generalizing from one example (and the more nootropics - or meditation styles, or self-help books, or getting things done systems - you try, the stronger the temptation is to evangelize). The best you can do is read all the testimonials and studies and use that to prioritize your list of nootropics to try. You don’t know in advance which ones will pay off and which will be wasted. You can’t know in advance. And wasted some must be; to coin a Umeshism: if all your experiments work, you’re just fooling yourself. (And the corollary - if someone else’s experiments always work, they’re not telling you everything.)

We reached out to several raw material manufacturers and learned that Phosphatidylserine and Huperzine A are in short supply. We also learned that these ingredients can be pricey, incentivizing many companies to cut corners.  A company has to have the correct ingredients in the correct proportions in order for a brain health formula to be effective. We learned that not just having the two critical ingredients was important – but, also that having the correct supporting ingredients was essential in order to be effective.


In addition to diet, there are many other things you can also do related to lifestyle, such as stress management through mindfulness (8) or gentle movement such as pre or post natal yoga (9), which have both shown to be incredibly helpful in encouraging mental wellbeing. If you feel you need extra support, personalised nutritional therapy can be very helpful as there can often be other drivers such as nutrient deficiencies and digestive complaints that can play a significant role in mental health and will need to be addressed in a way that is tailored to the individual. 

These superfoods contain powerful antioxidants that can protect your brain from toxic free radicals. One study of older women found that those who ate the most green, leafy vegetables had minds that functioned like those of women who were one to two years younger than they were, compared to women who ate fewer leafy greens, according to the Alzheimer’s Association. Here are some habits that will keep your brain healthy throughout your entire life.


Common environmental toxins – pesticides, for example – cause your brain to release glutamate (a neurotransmitter). Your brain needs glutamate to function, but when you create too much of it it becomes toxic and starts killing neurons. Oxaloacetate protects rodents from glutamate-induced brain damage.[17] Of course, we need more research to determine whether or not oxaloacetate has the same effect on humans.
Whole grains. Whole grains, such as oatmeal, whole-grain breads, and brown rice can reduce the risk for heart disease. "Every organ in the body is dependent on blood flow," says Pratt. "If you promote cardiovascular health, you're promoting good flow to the organ system, which includes the brain." While wheat germ is not technically a whole grain, it also goes on Kulze's "superfoods" list because in addition to fiber, it has vitamin E and some omega-3s. Kulze suggests 1/2 cup of whole-grain cereal, 1 slice of bread two-thee times day, or 2 tablespoons of wheat germ a day.
Our 2nd choice for a Brain and Memory supplement is Clari-T by Life Seasons. We were pleased to see that their formula included 3 of the 5 necessary ingredients Huperzine A, Phosphatidylserine and Bacopin. In addition, we liked that their product came in a vegetable capsule. The product contains silica and rice bran, though, which we are not sure is necessary.
I took the pill at 11 PM the evening of (technically, the day before); that day was a little low on sleep than usual, since I had woken up an hour or half-hour early. I didn’t yawn at all during the movie (merely mediocre to my eyes with some questionable parts)23. It worked much the same as it did the previous time - as I walked around at 5 AM or so, I felt perfectly alert. I made good use of the hours and wrote up my memories of ICON 2011.
Kratom (Erowid, Reddit) is a tree leaf from Southeast Asia; it’s addictive to some degree (like caffeine and nicotine), and so it is regulated/banned in Thailand, Malaysia, Myanmar, and Bhutan among others - but not the USA. (One might think that kratom’s common use there indicates how very addictive it must be, except it literally grows on trees so it can’t be too hard to get.) Kratom is not particularly well-studied (and what has been studied is not necessarily relevant - I’m not addicted to any opiates!), and it suffers the usual herbal problem of being an endlessly variable food product and not a specific chemical with the fun risks of perhaps being poisonous, but in my reading it doesn’t seem to be particularly dangerous or have serious side-effects.

Though their product includes several vitamins including Bacopa, it seems to be missing the remaining four of the essential ingredients: DHA Omega 3, Huperzine A, Phosphatidylserine and N-Acetyl L-Tyrosine. It missed too many of our key criteria and so we could not endorse this product of theirs. Simply, if you don’t mind an insufficient amount of essential ingredients for improved brain and memory function and an inclusion of unwanted ingredients – then this could be a good fit for you.

(If I am not deficient, then supplementation ought to have no effect.) The previous material on modern trends suggests a prior >25%, and higher than that if I were female. However, I was raised on a low-salt diet because my father has high blood pressure, and while I like seafood, I doubt I eat it more often than weekly. I suspect I am somewhat iodine-deficient, although I don’t believe as confidently as I did that I had a vitamin D deficiency. Let’s call this one 75%.
The fact is, many of these compounds in small amounts and less frequent use can be relatively safe, but as you’re probably not surprised to hear, I’m not 100% convinced of the overall long-term safety or efficacy of most smart drugs used frequently or in moderate to high dosages for the reasons stated above. It is true that some are slightly less risky than others and are increasing in popularity among biohackers and medical professionals. They’re also becoming used with high frequency by students, athletes and e-gamers, three populations for which smart drug “doping control” is becoming more frequently banned and considered to be illegal use of performance-enhancing drugs. Yes, “brain doping” and “brain PED’s” (brain Performance Enhancing Drugs) are now a thing. But I’d consider carefully the use of smart drugs as daily go-to brain enhancing supplements, especially in light of the safer alternative you’re about to discover: the entire category of natural and synthetic nootropic compounds.
She speaks from professional and personal experience. When she first moved to the United States from Italy at age 24 she was struck by how shifting from the Mediterranean-style diet she grew up on to a standard American diet negatively impacted her physical health and work performance. The experience led her to more closely study nutrition and the link between diet and brain health. In this excerpt from a longer interview, she discusses the brain foods you should be eating.
TianChi Chinese Adaptogenic Herb Complex: The list of herbs and ingredients in the supplement TianChi is far too long to include here, but in short, it contains nearly every natural Chinese adaptogen and natural nootropic you’ve read about so far in this article. So when it comes to a purely non-synthetic approach to mental enhancement, this blend tops the totem pole. All of the herbs in TianChi are wildcrafted (gathering of plants from their native “wild” environment) or organic, non-GMO, Kosher Certified, non-irradiated and pesticide free, then formulated in small batches by a Chinese herbal medicine practitioner in Oregon. The herbs are extracted in purified water and test free of heavy metals. Most adaptogens purchased in today’s market are standardized 5:1 extract; meaning that it takes five pounds of herb to make one pound of extract. This is not always effective as some herbs may have to extract out at 10:1 in order to gain their natural strength. In contrast, the adaptogens in TianChi are extracted at a 45:1 ratio, making this one of the more potent blends out there. Strangely enough, I’ve found the brain-boosting effects of TianChi to be even more enhanced when consumed with beet juice or beet powder, probably due to the vasodilation effect of the beets. This is one of my favorite blends to mix up on a mid-morning or mid-afternoon an empty stomach for a very clear-headed cognitive high.

The first night I was eating some coconut oil, I did my n-backing past 11 PM; normally that damages my scores, but instead I got 66/66/75/88/77% (▁▁▂▇▃) on D4B and did not feel mentally exhausted by the end. The next day, I performed well on the Cambridge mental rotations test. An anecdote, of course, and it may be due to the vitamin D I simultaneously started. Or another day, I was slumped under apathy after a promising start to the day; a dose of fish & coconut oil, and 1 last vitamin D, and I was back to feeling chipper and optimist. Unfortunately I haven’t been testing out coconut oil & vitamin D separately, so who knows which is to thank. But still interesting.
The evidence? Although everyone can benefit from dietary sources of essential fatty acids, supplementation is especially recommended for people with heart disease. A small study published in 2013 found that DHA may enhance memory and reaction time in healthy young adults. However, a more recent review suggested that there is not enough evidence of any effect from omega 3 supplementation in the general population.
I’ve been actively benefitting from nootropics since 1997, when I was struggling with cognitive performance and ordered almost $1000 worth of smart drugs from Europe (the only place where you could get them at the time). I remember opening the unmarked brown package and wondering whether the pharmaceuticals and natural substances would really enhance my brain.
Fortunately for me, the FDA decided Smart Powder’s advertising was too explicit and ordered its piracetam sales stopped; I was equivocal at the previous price point, but then I saw that between the bulk discount and the fire-sale coupon, 3kg was only $99.99 (shipping was amortized over that, the choline, caffeine, and tryptophan). So I ordered in September 2010. As well, I had decided to cap my own pills, eliminating the inconvenience and bad taste. 3kg goes a very long way so I am nowhere close to running out of my pills; there is nothing to report since, as the pills are simply part of my daily routine.

I was contacted by the Longecity user lostfalco, and read through some of his writings on the topic. I had never heard of LLLT before, but the mitochondria mechanism didn’t sound impossible (although I wondered whether it made sense at a quantity level14151617), and there was at least some research backing it; more importantly, lostfalco had discovered that devices for LLLT could be obtained as cheap as $15. (Clearly no one will be getting rich off LLLT or affiliate revenue any time soon.) Nor could I think of any way the LLLT could be easily harmful: there were no drugs involved, physical contact was unnecessary, power output was too low to directly damage through heating, and if it had no LLLT-style effect but some sort of circadian effect through hitting photoreceptors, using it in the morning wouldn’t seem to interfere with sleep.


This research is in contrast to the other substances I like, such as piracetam or fish oil. I knew about withdrawal of course, but it was not so bad when I was drinking only tea. And the side-effects like jitteriness are worse on caffeine without tea; I chalk this up to the lack of theanine. (My later experiences with theanine seems to confirm this.) These negative effects mean that caffeine doesn’t satisfy the strictest definition of nootropic (having no negative effects), but is merely a cognitive enhancer (with both benefits & costs). One might wonder why I use caffeine anyway if I am so concerned with mental ability.
Somewhat ironically given the stereotypes, while I was in college I dabbled very little in nootropics, sticking to melatonin and tea. Since then I have come to find nootropics useful, and intellectually interesting: they shed light on issues in philosophy of biology & evolution, argue against naive psychological dualism and for materialism, offer cases in point on the history of technology & civilization or recent psychology theories about addiction & willpower, challenge our understanding of the validity of statistics and psychology - where they don’t offer nifty little problems in statistics and economics themselves, and are excellent fodder for the young Quantified Self movement4; modafinil itself demonstrates the little-known fact that sleep has no accepted evolutionary explanation. (The hard drugs also have more ramifications than one might expect: how can one understand the history of Southeast Asia and the Vietnamese War without reference to heroin, or more contemporaneously, how can one understand the lasting appeal of the Taliban in Afghanistan and the unpopularity & corruption of the central government without reference to the Taliban’s frequent anti-drug campaigns or the drug-funded warlords of the Northern Alliance?)
Though coffee gives instant alertness and many cups of the beverage are downed throughout the day, the effect lasts only for a short while. People who drink coffee every day may develop caffeine tolerance; this is the reason why it is still important to control your daily intake. It is advisable that an individual should not consume more than 300mg of coffee a day. Caffeine, the world’s favourite nootropic has very less side effects but if consumed abnormally high can result in nausea, restlessness, nervousness and hyperactivity. This is the reason why people who need increased sharpness would rather induce L-theanine, or some other Nootropic, along with caffeine. Today, you can find various smart drugs that contain caffeine in them. OptiMind , one of the best and most sought-after nootropic in the U.S, containing caffeine, is considered more effective and efficient when compared to other focus drugs present in the market today.
Does little alone, but absolutely necessary in conjunction with piracetam. (Bought from Smart Powders.) When turning my 3kg of piracetam into pills, I decided to avoid the fishy-smelling choline and go with 500g of DMAE (Examine.com); it seemed to work well when I used it before with oxiracetam & piracetam, since I had no piracetam headaches, and be considerably less bulky.
I am sort of a health nut. I only use natural medicines- never prescriptions. Lately I have been experiencing some brain fog in spite of my detoxing, so I tried this product. I LOVE IT! I really can tell a difference. I have tried many memory and brain support supplements before, but this one seems quite different. I love the daytime and separate night time formulas. I have never slept so soundly in my life. In fact, I've always had a lot of trouble sleeping, but I sleep like a baby and wake feeling refreshed and full of energy.
The body has its own inherent detoxification pathways that are responsible for packaging and removing heavy metals safely from the system. For example, glutathione is known as the body’s ‘master antioxidant’ and aside from playing an important role in preventing free radicals from causing damage to the body’s cells, it also helps to bind to heavy metals and remove them from the body. Research shows that glutathione levels are lower than normal in those on the autism spectrum, so enhancing levels through the diet may be an effective way to prevent the accumulation of heavy metals. Consuming sulfur-rich foods such as broccoli, cabbage, onions, garlic, kale and cauliflower can boost glutathione levels, as well as milk thistle, which has unique flavonoids that also support glutathione production.
“By drawing on more than fifteen years of scientific research and experience, Dr. Mosconi provides expert advice to prevent medical decline and sharpen memory. Her brain healthy recipes will help you maintain peak cognitive performance well into old age and therefore delay and may even prevent the appearance of debilitating diseases like Alzheimer’s.”
But notice that most of the cost imbalance is coming from the estimate of the benefit of IQ - if it quadrupled to a defensible $8000, that would be close to the experiment cost! So in a way, what this VoI calculation tells us is that what is most valuable right now is not that iodine might possibly increase IQ, but getting a better grip on how much any IQ intervention is worth.
Thanks to its carefully-selected and totally harmless natural ingredients, you can deal with stressful situations more efficiently and overcome them easier. We are exposed to stress from diverse sources, such as family, school or work. If you feel that you constantly lack the energy to get your things done, then you can freely blame it on stress. Brain Pill helps you get rid of brain fog that limits your productivity and alertness levels.
For obvious reasons, it’s difficult for researchers to know just how common the “smart drug” or “neuro-enhancing” lifestyle is. However, a few recent studies suggest cognition hacking is appealing to a growing number of people. A survey conducted in 2016 found that 15% of University of Oxford students were popping pills to stay competitive, a rate that mirrored findings from other national surveys of UK university students. In the US, a 2014 study found that 18% of sophomores, juniors, and seniors at Ivy League colleges had knowingly used a stimulant at least once during their academic career, and among those who had ever used uppers, 24% said they had popped a little helper on eight or more occasions. Anecdotal evidence suggests that pharmacological enhancement is also on the rise within the workplace, where modafinil, which treats sleep disorders, has become particularly popular.
But how to blind myself? I used my pill maker to make 9 OO pills of piracetam mix, and then 9 OO pills of piracetam mix+the Adderall, then I put them in a baggy. The idea is that I can blind myself as to what pill I am taking that day since at the end of the day, I can just look in the baggy and see whether a placebo or Adderall pill is missing: the big capsules are transparent so I can see whether there is a crushed-up blue Adderall in the end or not. If there are fewer Adderall than placebo, I took an Adderall, and vice-versa. Now, since I am checking at the end of each day, I also need to remove or add the opposite pill to maintain the ratio and make it easy to check the next day; more importantly I need to replace or remove a pill, because otherwise the odds will be skewed and I will know how they are skewed. (Imagine I started with 4 Adderalls and 4 placebos, and then 3 days in a row I draw placebos but I don’t add or remove any pills; the next day, because most of the placebos have been used up, there’s only a small chance I will get a placebo…)

Cocoa flavanols (CF) positively influence physiological processes in ways which suggest that their consumption may improve aspects of cognitive function. This study investigated the acute cognitive and subjective effects of CF consumption during sustained mental demand. In this randomized, controlled, double-blinded, balanced, three period crossover trial 30 healthy adults consumed drinks containing 520 mg, 994 mg CF and a matched control, with a 3-day washout between drinks. Assessments included the state anxiety inventory and repeated 10-min cycles of a Cognitive Demand Battery comprising of two serial subtraction tasks (Serial Threes and Serial Sevens), a Rapid Visual Information Processing (RVIP) task and a mental fatigue scale, over the course of 1 h. Consumption of both 520 mg and 994 mg CF significantly improved Serial Threes performance. The 994 mg CF beverage significantly speeded RVIP responses but also resulted in more errors during Serial Sevens. Increases in self-reported mental fatigue were significantly attenuated by the consumption of the 520 mg CF beverage only. This is the first report of acute cognitive improvements following CF consumption in healthy adults. While the mechanisms underlying the effects are unknown they may be related to known effects of CF on endothelial function and blood flow.


Tyrosine (Examine.com) is an amino acid; people on the Imminst.org forums (as well as Wikipedia) suggest that it helps with energy and coping with stress. I ordered 4oz (bought from Smart Powders) to try it out, and I began taking 1g with my usual caffeine+piracetam+choline mix. It does not dissolve easily in hot water, and is very chalky and not especially tasty. I have not noticed any particular effects from it.
Provigil may well confer a temporary advantage on healthy people, but this doesn't mean that it's ready to replace your morning espresso. Anjan Chatterjee told me that there "just aren't enough studies of these drugs in normal people". One study, published recently in the Journal of the American Medical Association, suggests that Provigil can be habit-forming. A group led by Nora Volkow, the director of the National Institute on Drug Abuse, scanned the brains of 10 men after they had been given a placebo, and also after they had been given a dose of modafinil. The modafinil appeared to lead to an increase in the brain chemical dopamine. "Because drugs that increase dopamine have the potential for abuse," Volkow's report concluded, "these results suggest that risk for addiction in vulnerable persons merits heightened awareness." (Cephalon, in a response to the report, notes that Provigil's label urges physicians to monitor patients closely, especially those with a history of drug abuse.) On the website Erowid, where people vividly and anonymously report their experiences with legal and illegal drugs, some modafinil users have described a dependency on the drug. One man, who identified himself as a former biochemistry student, said that he had succeeded in kicking cocaine and opiate habits but couldn't stop using modafinil. Whenever he ran out of the drug, he said, "I start to freak out." After "four to five days" without it, "the head fog starts to come back".
Exercise is also important, says Lebowitz. Studies have shown it sharpens focus, elevates your mood and improves concentration. Likewise, maintaining a healthy social life and getting enough sleep are vital, too. Studies have consistently shown that regularly skipping out on the recommended eight hours can drastically impair critical thinking skills and attention.
The evidence? Found helpful in reducing bodily twitching in myoclonus epilepsy, a rare disorder, but otherwise little studied. Mixed evidence from a study published in 1991 suggests it may improve memory in subjects with cognitive impairment. A meta-analysis published in 2010 that reviewed studies of piracetam and other racetam drugs found that piracetam was somewhat helpful in improving cognition in people who had suffered a stroke or brain injury; the drugs’ effectiveness in treating depression and reducing anxiety was more significant.

Not all drug users are searching for a chemical escape hatch. A newer and increasingly normalized drug culture is all about heightening one’s current relationship to reality—whether at work or school—by boosting the brain’s ability to think under stress, stay alert and productive for long hours, and keep track of large amounts of information. In the name of becoming sharper traders, medical interns, or coders, people are taking pills typically prescribed for conditions including ADHD, narcolepsy, and Alzheimer’s. Others down “stacks” of special “nootropic” supplements.


Forums including reddit.com/r/Nootropics/ have more than 140,000 subscribers discussing products with names like Orange Brainwash and GodMode. Nootropics are blends of ingredients touted as a low-risk way to enhance learning, memory, motivation, and even serenity. These ingredients range from herbs such as water hyssop (Bacopa monnieri) and arctic root to chemicals such as vinpocetine.
Perhaps the most well-known natural nootropic stimulant and neuroenhancer is caffeine. Caffeine has been shown to prevent memory deficits in experimental models of Alzheimer’s disease and may even restore memory following impairment. In studies performed with college students, caffeine was shown to have particularly potent effects on memory improvement during students’ non-optimal time of day, in this case, early in the morning. Caffeine’s benefits go even further because it’s never found in an isolated vacuum in nature, meaning that it’s always located in some kind of plant such as green tea or bean such as coffee that carry additional beneficial compounds which often enhance the effects of caffeine, including, most notably, certain cholesterols, polyphenols and antioxidants. In fact, one study determined that caffeine alone does not account for the benefits caused by coffee consumption. Rather, the phytochemical content of coffee (coffee contains over 1,000 different natural chemicals!) gives it potent antioxidant and anti-inflammatory properties that complement the neuroprotective effects of caffeine on the central nervous system.
After trying out 2 6lb packs between 12 September & 25 November 2012, and 20 March & 20 August 2013, I have given up on flaxseed meal. They did not seem to go bad in the refrigerator or freezer, and tasted OK, but I had difficulty working them into my usual recipes: it doesn’t combine well with hot or cold oatmeal, and when I tried using flaxseed meal in soups I learned flaxseed is a thickener which can give soup the consistency of snot. It’s easier to use fish oil on a daily basis.
The single most reliable way to protect our brain cells as we age, most researchers agree, is to eat plenty of fruits and vegetables, which are chock-full of antioxidants and nutrients. In a study published in the October 1997 issue of the American Journal of Clinical Nutrition, researchers tested 260 people aged 65 to 90 with a series of mental exercises that involved memorizing words or doing mental arithmetic. The top performers were those who consumed the most fruits and vegetables and ate the least artery-clogging saturated fat.
In her new book, Brain Food: The Surprising Science of Eating for Cognitive Power (Avery/ Penguin Random House), Dr. Lisa Mosconi, PhD, INHC, Associate Director of the Alzheimer’s Prevention Clinic at Weill Cornell Medical College, highlights the connection between diet and brain function and shares approachable, actionable tips to put that research into practice.
Paul Phillips was unusual for a professional poker player. When he joined the circuit in the late 1990s he was already a millionaire: a twentysomething tech guy who helped found an internet portal called go2net and cashed in at the right moment. He was cerebral and at times brusque. On the international poker scene Phillips cultivated a geeky New Wave style. He wore vintage shirts in wild geometric patterns; his hair was dyed orange or silver one week, shaved off the next. Most unusual of all, Phillips talked freely about taking prescription drugs - Adderall and, especially, Provigil - in order to play better cards.
Ampakines are structurally derived from a popular nootropic called “aniracetam”. Their basic function is to activate AMPA glutamate receptors (AMPARs). Glutamate (a neurotransmitter) is the primary mediator of excitatory synaptic transmission in mammalian brains, which makes it crucial for synaptic plasticity (the adaptation of synapses, the space between neurons across which information is sent), learning and memory, so when you activate or stimulate glutamate receptors, you can trigger many of these functions. AMPARs are distributed across the central nervous system and are stimulated by incoming glutamate to begin the neuroenhancing benefits they’re often used for. But it is possible to have too much glutamate activity. When excess glutamate is produced, accumulates and binds to AMPARs, the result is excitotoxicity, which is a state of cell death (in the case of the central nervous system and your brain, neuron death) resulting from the toxic levels of excitatory amino acids. Excitotoxicity is believed to play a major role in the development of various degenerative neurological conditions such as schizophrenia, delirium and dementia.
It’s that time of the year again. It’s Blue Monday. We’re halfway into January, trudging through the deepest and darkest of the winter months, as we try to keep our heads high after the Christmas festivities with the motivation of our New Year’s resolutions. Some of you may have never heard of Blue Monday and let’s just say you’re not exactly missing out.

Any consideration of the future of nootropics is directly tied into the future of humanity. As long as work productivity demands continue to soar, there will like be a affiliated rise in the desire to increase brain power. As Vice discusses in a thoughtful article providing several insights into why nootropics are popular, it is not surprising that smart drugs and the nootropic industry are ever-expanding. Vice points out that sci-fi writers once warned of people being overtaken by machines, but instead, human beings are becoming machines, taking on unrealistic work levels.[15] Taking nootropic drugs is akin to loading up on premium fuel in an effort to go faster and do better.
Jump up ^ Greely, Henry; Sahakian, Barbara; Harris, John; Kessler, Ronald C.; Gazzaniga, Michael; Campbell, Philip; Farah, Martha J. (December 10, 2008). "Towards responsible use of cognitive-enhancing drugs by the healthy". Nature. Nature Publishing Group. 456 (7223): 702–705. Bibcode:2008Natur.456..702G. doi:10.1038/456702a. ISSN 1476-4687. OCLC 01586310. PMID 19060880. Retrieved March 25, 2014. (Subscription required (help)).
×