Improved Class of Ratio-Cum-Product Estimators of Finite Population Mean in two Phase Sampling. Global Journal of Science Frontier Research, [S. l.], v. 14, n. 16, p. 59–71, 2014. Disponível em: https://journalofscience.org/index.php/GJSFR/article/view/. Acesso em: 23 oct. 2026.