Shinozaki A, Shibahara J, Noda N, Tanaka M, Aoki T, Kokudo N, Fukayama M. Claudin-18 in biliary neoplasms. Its significance in the classification of intrahepatic cholangiocarcinoma. Virchows Arch. 2011 Jul;459(1):73–80. doi: 10.1007/s00428-011-1092-z. PMID: 21607649.