J.O. Muili, A. Audu , A.B. Odeyale , and I.O. Olawoyin. “Ratio Estimators for Estimating Population Mean Using Tri-Mean, Median and Quartile Deviation of Auxiliary Variable”. NIPES - Journal of Science and Technology Research, vol. 1, no. 1, Mar. 2019, https://journals.nipes.org/index.php/njstr/article/view/26.