0120-1263 0120-1263 S0120-12632018000200239 10.18566/escr.v26n57.a01 Colombia 00 12 2018 00 12 2018 26 57 239 248 2007 79-107 2018 26 56 56 21-61 1972 2003 2004 2002 1985 2007 1982