1870-199X 1870-199X S1870-199X2009000100009 10.22201/fo.1870199xp.2009.13.1.15613 Mexico Mexico 00 00 2009 00 00 2009 13 1 9 16

1 1999 206-7 2 1990 6 6 139 3 1941 2 223-5 4 1987 13 147 5 2000 33 46-52 6 2001 34 206-15 7 1982 3 17 8 1982 88 1 1 46-52 9 1999 41 101-5 10 1999 41 101-5 11 1990 69 491-501 12 1999 41 59-70 13 2003