@article{GAMA_1970_1970_1_a6,
     author = {Machado Da Silva, Fausto},
     title = {Tangentes a uma c\^onica.},
     journal = {Gaceta matem\'atica},
     pages = {93-97},
     publisher = {mathdoc},
     volume = {22},
     number = {3-4},
     year = {1970},
     url = {http://geodesic.mathdoc.fr/item/GAMA_1970_1970_1_a6/}
}