Gambaran patologi anatomi penyakit refluks gastroesofageal pada anak yang dilakukan endoskopi saluran cerna atas di Departemen IKA RSCM FKUI tahun 2011-2015 = Anatomical pathology findings of gastroesophageal reflux disease in chidren underwent upper gastrointestinal endoscopy at Department of Child Health of RSCM FKUI during 2011-2015