Nizami, Major Muhammad Asif, et al. “FREQUENCY OF VITAMIN B12 DEFICIENCY IN PATIENTS WITH HELICOBACTER PYLORI GASTRITIS: Vitamin B12 Deficiency”. Pakistan Armed Forces Medical Journal, vol. 62, no. 2, June 2012, pp. 203-5, https://pafmj.org/PAFMJ/article/view/1663.