@article{MET_1973__20_175606,
     author = {J. Lanke},
     title = {On {UMV-Estimators} in {Survey} {Sampling.}},
     journal = {Metrika},
     pages = {196--202},
     year = {1973},
     volume = {20},
     zbl = {0277.62008},
     url = {http://geodesic.mathdoc.fr/item/MET_1973__20_175606/}
}