Fonte:
http://www.dgaiec.min-financas.pt/NR/rdonlyres/DB579927-5862-4E40-AE6A-455C93BE0C00/0/Circular_n_12_2008_II.pdf
http://www.dgaiec.min-financas.pt/NR/rdonlyres/2F81C545-2872-499C-B6DF-1ECB3DCD850B/0/Circular_n_13_2008_II.pdf
