@article{GAMA_1970_1970_1_a11,
     author = {Laborde, P.},
     title = {On sets {S.}},
     journal = {Gaceta matem\'atica},
     pages = {144-147},
     publisher = {mathdoc},
     volume = {22},
     number = {5-6},
     year = {1970},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/GAMA_1970_1970_1_a11/}
}