"Thomas Young." The Columbia Encyclopedia, Sixth Edition. 2008. Encyclopedia.com. 23 Nov. 2009 <http://www.encyclopedia.com>.
"Thomas Young." The Columbia Encyclopedia, Sixth Edition. 2008. Encyclopedia.com. (November 23, 2009). http://www.encyclopedia.com/doc/1E1-Young-Th.html
"Thomas Young." The Columbia Encyclopedia, Sixth Edition. 2008. Retrieved November 23, 2009 from Encyclopedia.com: http://www.encyclopedia.com/doc/1E1-Young-Th.html