“Historical Perspective and Fundamentals of Clinical Research” (2020) African Journal of Biomedical Research, 23(Special Edition 2), पृ. 7–9. पर उपलब्ध: https://ojshostng.com/index.php/ajbr/article/view/87 (अंतिम उपयोग: 6 अप्रैल 2026).