@article{RSA_1957__5_1_57_0,
     author = {Ulmo, J. and Schwartz, D. and Vessereau, A.},
     title = {Probl\`emes relatifs aux \'echantillonnages \`a plusieurs niveaux},
     journal = {Revue de Statistique Appliqu\'ee},
     pages = {57--66},
     publisher = {Soci\'et\'e de Statistique de France},
     volume = {5},
     number = {1},
     year = {1957},
     language = {fr},
     url = {http://www.numdam.org/item/RSA_1957__5_1_57_0/}
}