Bhattarai, Aseem, Bharat Jha, and Santosh Timilsina. 2015. “Serum CA 19-9 Levels in Benign and Malignant Diseases Associated With the Gastrointestinal Tract”. Annals of Clinical Chemistry and Laboratory Medicine 1 (2):35-41. https://doi.org/10.3126/acclm.v1i2.13546.