2312-3893 2312-3893 S2312-38932019000100146 10.18004/rvspmi/2312-3893/2019.06(01)146-148 Paraguay 01 03 2019 01 03 2019 6 1 146 148 1 2018 5 2 2 105-9 2 2008 29 2 2 270-6 3 2018 20 2 2 228-39 4 2016 69 12 12 1167 5 2008 217 1 1 27-37 6 2015 28 1 1 1-39