2448-6442 2448-6442 S2448-64422017000300571 10.24201/es.2017v35n105.1434 Mexico Mexico 00 12 2017 00 12 2017 35 105 571 595

2006 77 5 5 684-711 2001 1975 217231 1971 1999 2000 2014 2009 4 3 3 321-36 2003 127-33 2001 1998 9 18 18 296-314 1997 1997 1993 1 1 1 17-32 2015 2009 2012 23 45 45 249-52 2009 2003 2012 2012 2006 1977 4 3 3 301-31 2004 10 5 5 673690 2008 2007 1997 3-18 1999 16 16 195-213 2007 2006 7 3 3 291-308 2005 12 3 3 329-44 2003 14 1 1 87-110 2015 5 9-1 9-1 249-58 National Union of Students (NUS) 2011 2011 1980 2002 2001 2010 31 2 2 175-98 2015 6-7 6-7 70-4