Tailor, R. ., and H. A. . Lone. “RATIO –CUM- PRODUCT ESTIMATOR OF FINITE POPULATION MEAN IN DOUBLE SAMPLING FOR STRATIFICATION”. Journal of Reliability and Statistical Studies, vol. 7, no. 01, June 2014, pp. 93-101, https://journals.riverpublishers.com/index.php/JRSS/article/view/21607.