Fonte:
http://www.dgaiec.min-financas.pt/NR/rdonlyres/142CF542-D9CA-4009-B42F-B864CAA9D7ED/0/Circular_n_113_2008_II.pdf
http://www.dgaiec.min-financas.pt/NR/rdonlyres/03775034-1E3E-4233-8A66-433393F623F2/0/Circular_n_114_2008_II.pdf