Pediatric gastroesophageal reflux clinical practice guidelines: joint recommendations of the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition (NASPGHAN) and the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN) - Vandenplas, Y; Rudolph, C D; Di Lorenzo, C (J Pediatr Gastroenterol Nutr, 2009)