1405-1079 1405-1079 S1405-10792020000200510 10.29265/gypp.v29i2.784 Ecuador 00 12 2020 00 12 2020 29 2 510 514 1984 16 2 2 223-46 1984 78 3 3 734-49 2000 94 2 2 251-67 2002 27 2 2 222-47 2005