Hasan, Najam Ul, et al. “ASSOCIATION OF VITAMIN B12 DEFICIENCY WITH INTAKE OF ORAL METFORMIN IN DIABETIC PATIENTS”. Journal of Ayub Medical College Abbottabad, vol. 31, no. 1, Dec. 2018, pp. 72-75, https://jamc.ayubmed.edu.pk/index.php/jamc/article/view/4321.