2550-6722 2550-6722 S2550-67222020000100041 10.37135/chk.002.10.03 Ecuador 00 04 2020 00 04 2020 10 41 59

1987 2012 2003 2011 1986 6 117-40 1987 7-29 1987 2016 1992 1968 1974 1972 2005 1999 2013 1 1 1 1997 1997 2017 2017 2006 2017 1981 1985