1990-8644 1990-8644 S1990-86442018000300020 República del Ecuador Cuba 00 06 2018 00 06 2018 14 63 20 24

(200 9) 12 2 2 73-82 Editorial Santillana (200 4) 2015 (200 6) (201 2) 15 1 1 (201 1) 36 4 4 204-18 (200 6) (201 4) 15 11 11 (201 3) 9 4 4 (200 3) 2 2 2 (200 9) 32 2 2 90-5