@article{RACSAM_2003_2003_1_a13, author = {Pedregal, Pablo}, title = {Sobre la estructura de gradientes sim\'etricos 2 x 2.}, journal = {Revista de la Real Academia de Ciencias Exactas, F{\'\i}sicas y Naturales. Matem\'aticas}, pages = {119-131}, publisher = {mathdoc}, volume = {97}, number = {1}, year = {2003}, language = {en}, url = {http://geodesic.mathdoc.fr/item/RACSAM_2003_2003_1_a13/} }