Fonte:
http://www.dgci.min-financas.pt/NR/rdonlyres/B707E26C-737C-42CA-8A51-2ACF374380D6/0/Circular_1_2008.pdf
http://www.dgci.min-financas.pt/NR/rdonlyres/4017ED61-253A-43E0-95D0-828875772D28/0/Circular_2_2008.pdf
