“IS A STUDY OF THE LEVEL OF CARBOHYDRATE ANTIGEN (CA 19-9) EFFECTIVE IN PATIENTS WITH COLORECTAL CANCER?”. Voprosy onkologii 66, no. 5 (May 1, 2020): 528–534. Accessed October 14, 2026. https://voprosyonkologii.ru/index.php/journal/article/view/1140.