0186-7210 0186-7210 S0186-72102008000200415 10.24201/edu.v23i2.1316 Canada 00 08 2008 00 08 2008 23 2 415 440

2005 13 13 232-59 2006 50 139 139 45-63 2003 2001 1984 1970 52 B B 1-13 1996 1992 2001 2001 38 12 12 2111-24 1995 1990 27 1 1 23-44 2000 2007 33 33 17-30 1999 31 1547-66 2001 38 12 12 2103-10 1996 15-32 2006 2003 1987 1994 1994 1994 14 14 83-101 1999 1978 10 10 1996 131-72 1980 2 1989 1992 2006 43-65 1996 1972 1998 Puebla 1993 25 8 8 1131-60 2002