Inci, Fatih, and Fatih Karatas. 2021. “The Relationship of Preoperative and Postoperative Serum CEA and CA 19-9 Levels With Tumor Localization, Stage and Overall Survival in Patients With Colorectal Cancer”. Annals of Medical Research 28 (4):0726-32. http://www.annalsmedres.org/index.php/aomr/article/view/465.