@article{MET_1989__36_3-4_176214,
     author = {A. Chaudhuri and A.K. Adhikary},
     title = {On {Efficiency} of the {Ratio} {Estimator.}},
     journal = {Metrika},
     pages = {55--59},
     year = {1989},
     volume = {36},
     number = {3-4},
     zbl = {0677.62005},
     url = {http://geodesic.mathdoc.fr/item/MET_1989__36_3-4_176214/}
}