Ardianto T, Warsinggih W, Seweng A. Correlation Between Histopathological Grading and Appearance of Obstruction With Level of Carsino-Embryonic Antigen (CEA) in Colorectal Carcinoma. IJSBAR. 2019;45(2):31-38. Accessed September 11, 2025. https://gssrr.org/JournalOfBasicAndApplied/article/view/9932