1. , . 2006. March of Dimes global report on birth defects: the hidden toll of dying and disabled children. White Plains, NY: March of Dimes.
2. Prevention of the First Occurrence of Neural-Tube Defects by Periconceptional Vitamin Supplementation
3. Food and Nutrition Board. 1998. Institute of Medicine (IOM). Dietary reference intakes for thiamin, riboflavin, niacin, folate, vitamin B12, pantothenic acid, biotin, and choline. A report of the Standing Committee on the Scientific Evaluation of Dietary Reference Intakes and its Panel on Folate, Other B Vitamins and Choline, and Subcommittee on Upper Reference Levels of Nutrients. Washington, DC: National Academy Press. 564p.