Jumaan, R. M. “Serum Copper, Zinc and Copper/Zinc Ratio and Their Relationship to Age and Growth Status in Yemeni Adolescent Girls”. Sultan Qaboos University Medical Journal, vol. 8, no. 3, Nov. 2008, pp. 291-9, https://journals.squ.edu.om/index.php/squmj/article/view/1376.