Fonte:
http://info.portaldasfinancas.gov.pt/NR/rdonlyres/23304C1D-1CA3-4AF2-A10F-F821BD93DE42/0/Circular%20E.pdf
http://info.portaldasfinancas.gov.pt/NR/rdonlyres/2E52B94F-5F51-4AE4-A849-A48CC222AA2C/0/Circular%20C.pdf
http://info.portaldasfinancas.gov.pt/NR/rdonlyres/064D89B4-F524-4E70-9F20-A6ACF84CA404/0/Circular%20B.pdf
http://info.portaldasfinancas.gov.pt/NR/rdonlyres/D41D1A8F-280D-4DCC-8521-999D0AFB654D/0/Circular%20A.pdf
