Pun, Ashis, Amit Dhungana, Jewan Pariyar, and UpadhyayHari Prasad. 2021. “Effectiveness of Fentanyl in Facilitating Cannulation of Ampulla of Vater During Endoscopic Retrograde Cholangiopancreatography”. Journal of Nepal Health Research Council 18 (4), 753-57. https://doi.org/10.33314/jnhrc.v18i4.3267.