Rizvi, Syed Ejaz Husain, Jaj P. Gupta, and Manoj Bhargava. “Effect of Optimum Stratification on Sampling With Varying Probabilities under Proportional Allocation”. Statistica 64, no. 4 (January 1, 2004): 721–733. Accessed April 25, 2024. https://rivista-statistica.unibo.it/article/view/68.