KUSANO, M. Interobserver and intraobserver variation in endoscopic assessment of GERD using "Los Angels" classification. Gastrointest Endosc. 1999, 49, 700-104
LOCKE, III. GR. Prevalence and clinical spectrum of gastroesophageal reflux a population-based study in Olmsted country, Minnesota. Gastroenterology. 1997, 112, 1448-1456