@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}, publisher = {mathdoc}, volume = {2}, number = {1}, year = {1999}, language = {es}, url = {http://geodesic.mathdoc.fr/item/GRSME_1999_1999_1_a2/} }