http://www.smithsonianmag.com/science-nature/this-is-how-your-brain-becomes-addicted-to-caffeine-26861037/?no-ist
http://www.collegiatetimes.com/opinion/columnists/article_65566b35-f4bb-5ac1-8b90-9551fe902d8e.html
http://www.eastbayexpress.com/LegalizationNation/archives/2014/03/07/caffeine-vs-thc-the-double-standards-of-addiction
http://www.urban75.com/Drugs/drugten.html
http://theweek.com/article/index/265333/why-all-drugs-should-be-legal-yes-even-heroin