"7-dehydrocholesterol." The American Heritage Stedman's Medical Dictionary. Houghton Mifflin Company, 2002. 21 Jan. 2007. Answers.com. Arquivado October 25, 2012, en Wayback Machine.
"7-dehydrocholesterol." The American Heritage Stedman's Medical Dictionary. Houghton Mifflin Company, 2002. 21 Jan. 2007. Answers.com. Arquivado October 25, 2012, en Wayback Machine.