References
- Bromwich , T. J. 1926 . I'A An Introduction to the Theory of Infinite Series, , 2nd revised ed. , New York : MacMillan and Co., Ltd. .
- Koop , J. C. 1951 . “A Note on the Bias of the Ratio Estimate,” . Bulletin Institut International de Statistique , 33 : 141 – 6 .
- Tin , M. 1965 . “Comparisons of Some Ratio Estimators,” . Journal of the American Statistical Association , 60 June : 294 – 307 .