Chaudhry, Muhammad Shahzad, and Muhammad Hanif. “Product and Exponential Product Estimators in Adaptive Cluster Sampling under Different Population Situations : Product Estimators in ACS ”. Proceedings of the Pakistan Academy of Sciences: A. Physical and Computational Sciences, vol. 53, no. 4, Apr. 2021, pp. 447-5, https://www.ppaspk.org/index.php/PPAS-A/article/view/265.