Primary paper: doi.org/10.1080/01621459.1952.10483446 . D. G. Horvitz and D. J. Thompson, Journal of the American Statistical Association 47(260), 663–685 (December 1952). University-hosted original scan: www.stat.cmu.edu/~brian/905-2008/papers/Horvitz-Thompson-1952-jasa.pdf . Publisher abstract describes a general treatment of finite-population sampling without replacement with unequal selection probabilities. Initial-only bylines retained.