Fonte:
http://info.portaldasfinancas.gov.pt/NR/rdonlyres/8FAE35C2-39E7-463D-B7D9-DD77A68AAB4C/0/ficha_doutrinaria_inf-vinc_Proc_1355_09.pdf
http://info.portaldasfinancas.gov.pt/NR/rdonlyres/BD22BC36-7830-4190-96DB-CC42571AE2D6/0/CIRS_Art_10.pdf
