2477-9199 2477-9199 S2477-91992020000200238 10.26807/cav.v0i09.259 Ecuador 00 12 2020 00 12 2020 9 238 242

2018 15 15 1880-920 2018 2018 155-8 2018 48 48 77-108 2014 9 1 1 35-67 2016 47 39-56