Supplemental - Watson and Crick discover chemical structure of DNA -- History.com This Day in History -- 2/28/1953

http://www.history.com/this-day-in-history/watson-and-crick-discover-chemical-structure-of-dna?et_cid=59750568&et_rid=954119701&linkid=http%3a%2f%2fwww.history.com%2fthis-day-in-history%2fwatson-and-crick-discover-chemical-structure-of-dna