Fonte:
http://www.dgci.min-financas.pt/NR/rdonlyres/1F88D639-062B-402D-B1B8-2137356554C9/0/Circular_2_2007.pdf
http://www.dgci.min-financas.pt/NR/rdonlyres/2827D946-28B2-4CDA-BFF7-3C8431B2F7CA/0/Circular_3_2007.pdf
