Buchari, Unni Bayani, Adi Muradi Muhar, and Asrul . 2018. “The CEA Value Based on Age, Location and Histopathology Degree of Tumor Factors in Colorectal Cancer Patients at Haji Adam Malik General Hospital Medan in 2011-2015”. International Journal of Medical Science and Clinical Invention 5 (5):3848-51. https://doi.org/10.18535/ijmsci/v5i5.19.