1870-199X 1870-199X S1870-199X2009000200115 10.22201/fo.1870199xp.2009.13.2.15610 Mexico Mexico Mexico Mexico 00 00 2009 00 00 2009 13 2 115 121

1 1992 41 3 2 1976 4 77-83 3 1983 18 655-68 4 1985 5 8-13 5 1985 5 8-13 6 1989 60 599-603 7 2003 8 303-20 8 1985 56 715-20 9 2000 343-55 10 1986 13 182-5 11 1999 70 909-13 12 2004 4 569-91 13 1957 75 358-62 14 2002 295-308 15 1997 18 214-22 16 2004 16 1 1 18-22 17 2002 73 748-53 18 2002 14 4 4 150-66 19 1998 4 1 1 75-82 19 1996 2 3 3 209-17 20 2001 254-66 21 2000 20 553-9 22 2000 19 21-39 23 1997 276 276 75-81 24 2000 22 44-50 25 2007 15 35-8