Basit, Zeeshan, and M. Ishaq Bhatti. “Efficient Classes of Estimators of Population Variance in Two-Phase Successive Sampling Under Random Non-Response”. Statistica 82, no. 2 (April 5, 2023): 177–198. Accessed July 22, 2024. https://rivista-statistica.unibo.it/article/view/12686.