1. Tierney LM, McPhee SJ, Papdakis MA. Current Medical Diagnosis and Treatment. Stamford, CT: Appleton & Lange.
2. Rubenstein E, Federman DD. Scientific American Medicine. New York: Scientific American.
3. Werbach MR. Textbook of Nutritional Medicine. Tarzana, CA: Third Line Press.
4. Brally J, Lord RS. Laboratory Evaluations in Molecular Medicine. Norcross, GA: Institute for Advances in Molecular Medicine.
5. Lowering blood homocysteine with folic acid based supplements: meta-analysis of randomised trials;BMJ,1998