2007-0934 2007-0934 S2007-09342017000801887 10.29312/remexca.v8i8.711 Mexico Mexico Mexico 00 12 2017 00 12 2017 8 8 1887 1890

1993 7 7 2008 31 2 2 115-23 1981 1985 279-89 1990 3 3