1. Are Inventions Inevitable? A Note on Social Evolution
2. Singletons and multiples in scientific discovery: A chapter in the sociology of science;Merton;Proc Am Philosophical Soc,1961
3. Gladwell M. Annals of Innovation: In The Air. The New Yorker. May 12, 2008. http://www.newyorker.com/reporting/2008/05/12/080512fa_fact_gladwell Accessed November 14, 2016
4. Circadian rhythms and levels of beta-endorphin, ACTH, and cortisol during chronic methadone maintenance treatment in humans;Kreek;Life Sci,1983
5. Obese, a new mutation in the house mouse;Ingalls;J Hered,1950