Fonte:
http://www.dgaiec.min-financas.pt/NR/rdonlyres/F059C4DF-17B1-473E-B1D4-A9D4097450D2/0/Circular_n_36_2010_II.pdf
http://www.dgaiec.min-financas.pt/NR/rdonlyres/C324DD22-0A07-4E31-8407-9383FC232070/0/Circular_n_37_2010_II.pdf
http://www.dgaiec.min-financas.pt/NR/rdonlyres/DF73A9AF-F7E3-4DA1-A92F-5E719B4C76CB/0/Circular_n_38_2010_II.pdf
