Shrestha, S., B. Bhattarai, and R. Shah. “Preemptive Use of Small Dose Fentanyl Suppresses Fentanyl Induced Cough”. Kathmandu University Medical Journal, vol. 10, no. 4, Sept. 2014, pp. 16-19, doi:10.3126/kumj.v10i4.10988.