2631-2816 2631-2816 S2631-28162021000300013 10.32719/26312816.2022.5.1.r1 Ecuador 00 04 2021 00 04 2021 5 1 1999 2 2-3 2-3 87-105 2002 50 3 3 43-59 2006 108 6 6 1017-54