@article{QUE_1991_1991_1_a0,
     author = {Castillo, Joan del},
     title = {Muestreo y estimaci\'on de poblaciones ocultas.},
     journal = {Q\"uestii\'o},
     pages = {55-68},
     publisher = {mathdoc},
     volume = {15},
     number = {1},
     year = {1991},
     url = {http://geodesic.mathdoc.fr/item/QUE_1991_1991_1_a0/}
}