Sailo, S., M. Zodinpuia, and N. P. “Study of Morphine With Ropivacaine and Ropivacaine Alone for Caudal Epidural Analgesia in Children”. International Surgery Journal, vol. 7, no. 3, Feb. 2020, pp. 781-6, doi:10.18203/2349-2902.isj20200822.