Fonte:
http://www.dgaiec.min-financas.pt/NR/rdonlyres/4D393A3F-EC3F-47CC-898C-3C8F51C2A008/0/Circular_n_11_2008_II.pdf
http://www.dgaiec.min-financas.pt/NR/rdonlyres/DB579927-5862-4E40-AE6A-455C93BE0C00/0/Circular_n_12_2008_II.pdf
