GÜLŞEN, Mustafa, et al. “Gastric Juice Ascorbic Acid Concentrations in Helicobacter Pylori (+) and (-) Patients”. Turkish Journal of Gastroenterology, vol. 6, no. 1, Jan. 1995, pp. 102-4, https://turkjgastroenterol.org/index.php/tjg/article/view/581.