Amer Ibrahim Falah Al-Omari, New Product-Type Estimators for the Population Mean Using Quartiles of the Auxiliary Variable. journal = {International Journal of Mathematical and Computational Sciences}, [online]. World Academy of Science, Engineering and Technology. January 2009, vol. 25(1). 16 - 20 [viewed 24 September 2024]. Available from: https://publications.waset.org/pdf/6014.