POSTOPERATIVE ANALGESIC EFFICACY OF EPIDURAL MORPHINE IN PATIENTS UNDERGOING CESAREAN SECTION, HOSPITAL ALFREDO G. PAULSON. NOVEMBER AND DECEMBER 2019. (2020). Actas Médicas (Ecuador), 30(2), 77-83. https://actasmedicas.ec/index.php/am/article/view/40 (Original work published 2021)