Ray-Offor, Emeka, and Christopher Obiorah. “Upper Gastro-Intestinal Endoscopy in Port-Harcourt, Nigeria: An Audit”. The Nigerian Health Journal 14, no. 3 (December 25, 2015): 134. Accessed November 25, 2025. https://www.tnhjph.com/index.php/tnhj/article/view/171.