0376-7892 0376-7892 S0376-78922018000400006 10.4321/s0376-78922018000400006 00 12 2018 00 12 2018 44 4 377 377 1 2003 112 7 7 1929-35 2 2000 7 4 4 175-86 3 1984 15-39 4 2000 7 4 4 168-74