Singh, Housila P., Anjana Rathour, and Ramkrishna S. Solanki. “Improved Class of Estimators of Finite Population Mean Using Sampling Fraction and Information on Two Auxiliary Variables in Sample Surveys”. Statistica 73, no. 3 (January 1, 2013): 353–361. Accessed February 5, 2023. https://rivista-statistica.unibo.it/article/view/4329.