Setyawati, Katharina, et al. “The Role of Esophageal PH-Metri Test on Gastro-Esophageal Reflux Disease Diagnosis”. The Indonesian Journal of Gastroenterology, Hepatology, and Digestive Endoscopy, vol. 9, no. 3, Jan. 2008, pp. 91-97, doi:10.24871/93200891-97.