RT Journal Article SR Electronic T1 Evaluation of disease extent with the Crohn's disease endoscopic index of severity JF Gut JO Gut FD BMJ Publishing Group Ltd and British Society of Gastroenterology SP 1819 OP 1820 DO 10.1136/gutjnl-2013-305557 VO 62 IS 12 A1 Marteau, Philippe YR 2013 UL http://gut.bmj.com/content/62/12/1819.abstract AB