1659-4142 1659-4142 S1659-41422020000200137 10.15517/eci.v10i2.37108 Angola 00 12 2020 00 12 2020 10 2 137 154

2006 1981 1998 69-84 2010 2016 1948 2002 2011 2015 2016 2017 1970 2020 2005 2014 1997 1998 2015 2005 1999 1996