“Prevalence of Vitamin D Deficiency and Insufficiency Across Trimesters of Pregnancy in Maiduguri, Nigeria: A Cross-Sectional Study”. African Journal of Biomedical Research, vol. 24, no. 1, जनवरी, 2021, पृ. 53-57, https://www.ojshostng.com/index.php/ajbr/article/view/1689.