Vitamin Deficiency, Dependency, and Toxicity for The Merck Manual Professional Edition: http://www.merck.com/mmpe/sec01/ch004/ch004a.html
Johnson LE. Vitamin Deficiency, Dependency, and Toxicity for The Merck Manual Professional Edition: http://www.merck.com/mmpe/sec01/ch004/ch004a.html. 458-463. 2008; 8.