1. E. E. Ziegler , L. J.Filer and I. L. S. I.-N.Foundation, Present Knowledge in Nutrition, ILSI Press, 1996
2. G. F. Combs , The Vitamins, Elsevier Science, 2012
3. Recommended dietary intakes (RDI) of vitamin B-12 in humans
4. B. V. R. C. Gopalan and S. C.Balasubramanian, Nutritive Value of Indian Foods, National Institute of Nutrition, Hyderabad, India, 2000, p. 2000
5. Trends in analysis of vitamin B12