@article{MET_1994__41_5_176490,
     author = {Vidyasagar Ramchandra Padmawar},
     title = {Stratification, {Midzuno-Sen} {Strategy} and {Nonnegative} {Unbiased} {Variance} {Estimation.}},
     journal = {Metrika},
     pages = {21--27},
     publisher = {mathdoc},
     volume = {41},
     number = {5},
     year = {1994},
     zbl = {0791.62008},
     url = {http://geodesic.mathdoc.fr/item/MET_1994__41_5_176490/}
}