Noor-ul-Amin, Muhammad, and Aamir Raza. “Regression-in-Ratio Estimators for Population Mean by Using Robust Regression in Two Phase Sampling”. Journal of Reliability and Statistical Studies 14, no. 02 (October 8, 2021): 527–540. Accessed May 12, 2026. https://journals.riverpublishers.com/index.php/JRSS/article/view/20341.