Yusuf TE, Harewood GC, Clain JE, Levy MJ (January 2006). "International survey of knowledge of indications for EUS". Gastrointestinal Endoscopy. 63 (1): 107–111. doi:10.1016/j.gie.2005.09.032. PMID16377326.
Yusuf TE, Harewood GC, Clain JE, Levy MJ (January 2006). "International survey of knowledge of indications for EUS". Gastrointestinal Endoscopy. 63 (1): 107–111. doi:10.1016/j.gie.2005.09.032. PMID16377326.