Keenan Joseph, Mallery Shawn, Freeman Martin L
Division of Gastroenterology, Hennepin County Medical Center and University of Minnesota, Minneapolis, MN 55415, USA.
Gastrointest Endosc. 2007 Oct;66(4):850-3. doi: 10.1016/j.gie.2007.01.005. Epub 2007 Aug 24.