0185-3929 0185-3929 S0185-39292008000400231 Mexico 00 00 2008 00 00 2008 29 116 231 253

1991 1 2 2 1992 2001 14 14 102-25 2007 1989 1998 7 7 1992 2000 1980 2004 2006 2003 2003 1998 1 1 1 2003 1994 2004 1991 18 2 2 1967 1998 8 8 1998 2001 2003 1998 3 3 2000 57 57 2001 1998 1986 2003 1999 10 10 2000 2001 1996 2001 6 6 2004 2002 9 9 1998 1992 46 46 1992 17 17 1996 1996 1998 1992 1991 1 2 2 1989 16 3 3 1995 2001 2003 2003 2003 2001 2002 28 61 61 2002 1998 2003 2000 2001 1998 2007 2002 1959 1971 1977 1996 2003 2002 1993 1977 1991 1934 2004 15 15 1995 1993 1955 1988 2001 1999 1997 1998 2002 28 61 61 2003 1998