Danish, F., S. Rizvi, M. I. Jeelani, and J. A. Reashi. “Obtaining Strata Boundaries under Proportional Allocation With Varying Cost of Every Unit”. Pakistan Journal of Statistics and Operation Research, Vol. 13, no. 3, Sept. 2017, pp. 567-74, doi:10.18187/pjsor.v13i3.1719.