CANORUÇ, Naime, et al. “THE ROLE OF THE LEVEL OF THE SERUM Cu, Zn, Ca, IN THE GASTROINTESTINAL CARCINOMA DIAGNOSIS”. Turkish Journal of Gastroenterology, vol. 4, no. 1, Jan. 1993, pp. 157-60, https://www.turkjgastroenterol.org/index.php/tjg/article/view/234.