M. Kürşat TÜRKDOĞAN, et al. “Serum and Tissue Levels of Vitamin A and E Gastric and Esophageal Cancer”. Turkish Journal of Gastroenterology, vol. 7, no. 4, July 2019, pp. 327-30, https://turkjgastroenterol.avesjournals.com/index.php/tjg/article/view/1174.