Influencing Factors of Difficulties in Elective Endotracheal Intubation during Endoscopic Retrograde Cholangiopancreatography 
ZHANG Hao1,GAO Li-li2,XUE Bing1,CAI Lei1*
Chinese General Practice . 2018, (14): 1689 -1693 .  DOI: 10.3969/j.issn.1007-9572.2018.00.028