1) Institute of Medicine. Food and Nutrition Board. Dietary Reference Intakes: Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. Washington, DC: National Academy Press, 1998.
2) Clarke R. (2008). B-vitamins and prevention of dementia. The Proceedings of the Nutrition Society, 67(1), 75–81.
3) Andrès, E., Federici, L., Affenberger, S., Vidal-Alaball, J., Loukili, N. H., Zimmer, J., & Kaltenbach, G. (2007). B12 deficiency: a look beyond pernicious anemia. The Journal of family practice, 56(7), 537–542.
4) Klee G. G. (2000). Cobalamin and folate evaluation: measurement of methylmalonic acid and homocysteine vs vitamin B(12) and folate. Clinical chemistry, 46(8 Pt 2), 1277–1283.