D. B. Kim, I. H. Jo, C.-N. Paik, Y.-J. Kim, and J. M. Lee, “Serum Pepsinogen and Gastrin Levels: Reliable Markers to Predict Small Intestinal Bacterial Overgrowth”, Turkish Journal of Gastroenterology, vol. 33, no. 3, pp. 213–220, Jan. 2022.