(en) Qin XL, Wang ZR, Shi JS, Lu M, Wang L, He QR (Feb 2004). Utility of serum CA19-9 in diagnosis of cholangiocarcinoma: In comparison with CEA. World Journal of Gastroenterology10(3): 427-432. PMID14760772. PMC4724921. DOI: 10.3748/wjg.v10.i3.427.
(en) Qin XL, Wang ZR, Shi JS, Lu M, Wang L, He QR (Feb 2004). Utility of serum CA19-9 in diagnosis of cholangiocarcinoma: In comparison with CEA. World Journal of Gastroenterology10(3): 427-432. PMID14760772. PMC4724921. DOI: 10.3748/wjg.v10.i3.427.