Gustavsson , Sven, Olof Nyrén, and Bo-Göran Widman. “Time Trends in Peptic Ulcer Surgery in Sweden: A Preliminary Report of a Nation-Wide Survey”. Upsala Journal of Medical Sciences 93, no. 2 (September 1, 1988): 149-154. Accessed March 25, 2026. https://ujms.net/index.php/ujms/article/view/6848.