Nuanpan Nangsue,  Adjusted Ratio and Regression Type Estimators for Estimation of Population Mean when some Observations are missing.   journal   = {International Journal of Mathematical and Computational Sciences}, [online]. World Academy of Science, Engineering and Technology.
    May 2009, vol. 29(5). 334 - 337
    [viewed 26 April 2024]. Available from: https://publications.waset.org/pdf/14354.