@article{063171609,
title = "Finding optimal estimators in survey sampling using unbiased estimators of zero",
author = "Tapan, K. Nayak",
year = "2003",
journal = "Journal of Statistical Planning and Inference",
volume = "114",
number = "1-2",
pages = "21-30",
issn = "0378-3758",
doi = "10.1016/s0378-3758(02)00460-3",
url = "https://eurekamag.com/research/063/171/063171609.php"
}