Fonte:
http://www.dgaiec.min-financas.pt/NR/rdonlyres/990A803A-C934-439E-93BD-D1515959E980/0/Circular_n_70_2008_II.pdf
http://www.dgaiec.min-financas.pt/NR/rdonlyres/1D62A2E4-2F1B-4CA5-96DF-C673104D4C20/0/Circular_n_71_2008_II.pdf
