Güler Doğanay, Perihan Ekmekçi, Baturay Kansu Kazbek, Hakan Yılmaz, Gülbanu Erkan, and Filiz Tüzüner. “Effects of Alfentanil or Fentanyl Added to Propofol for Sedation in Colonoscopy on Cognitive Functions: Randomized Controlled Trial”. Turkish Journal of Gastroenterology 28, no. 6 (July 25, 2019): 453–459. Accessed July 9, 2025. https://turkjgastroenterol.avesjournals.com/index.php/tjg/article/view/3450.