M. Niafar, B. Jamali, N. Lotfibakhshaiesh, N. Aghamohammadzadeh, and N. Nader, “The role of metformin on serum vitamin B12 levels in patients with type 2 diabetes mellitus”, Eur Res J, vol. 1, no. 1, pp. 1–7, Mar. 2015, doi: 10.18621/eurj.2015.1.1.1.