Hanif, MMukhopadhyah, PBhattachayrra, S2013-08-122013-08-121993Pakistan Journal of Statistics,v. 9,no.2,p.123-136http://hdl.handle.net/10263/5551enHorvitz–Thompson estimatorSuperpopulationStratified sampleOn estimating the variance of Horvitz - Thompson estimatorArticle