Singh, Y Menon, G Sandweep Sharma, Opendra Salam, and B K Sinha. “Understanding Chao (Biometrika, 1982) [Paper on ΠPS Sampling Schemes]”. International Journal of Statistical Sciences 24, no. 1 (March 28, 2024): 133–154. Accessed September 21, 2025. https://www.banglajol.info/index.php/ijss/article/view/72032.