@article{GRSME_1999_1999_1_a2,
     author = {C\'ordoba, Antonio},
     title = {Por el giro de una aguja.},
     journal = {La Gaceta de la Real Sociedad Matem\'atica Espa\~nola},
     pages = {58-65},
     year = {1999},
     volume = {2},
     number = {1},
     language = {es},
     url = {http://geodesic.mathdoc.fr/item/GRSME_1999_1999_1_a2/}
}