4Yasuda K,MukaiH,Cho E, et al. The use of endoscopic ultrasonography in the diagnosis and staging of carcinoma of the papilla of Vater[J]. Endoscopy,1998 20:218-222.
5Itoh A,Tsukamoto Y, NaitohY, et al. Interaductal ultrasonography for the examination of duodenal papillary region [J].J Ultrasound Med, 1994,13:679-684.