Said Ali Al-Hadhrami,  Ratio Type Estimators of the Population Mean Based on Ranked Set Sampling.   journal   = {International Journal of Mathematical and Computational Sciences}, [online]. World Academy of Science, Engineering and Technology.
    November 2009, vol. 35(11). 896 - 900
    [viewed 25 April 2024]. Available from: https://publications.waset.org/pdf/8713.