0034-7744 0034-7744 S0034-77442018000200481 10.15517/rbt.v66i2.33375 Costa Rica 00 06 2018 00 06 2018 66 2 481 485

1995 76-83 2002 50 3-4 3-4 xix-xxiii 2017 65 2 2 643-55 2017 65 2 2 657-68 1991 55-74