Verma, V. K., R. K. Nim, P. S. Singh, M. Kumar, G. Singh, and A. K. Singh. “Vitamin B12 Deficiency Among Vegetarian and Non-Vegetarian Diabetic Population Receiving Prolonged Metformin Based Oral Hypoglycemic Agents Therapy”. International Journal of Advances in Medicine, vol. 4, no. 4, July 2017, pp. 1150-4, doi:10.18203/2349-3933.ijam20173249.