Fonte:
http://www.dgaiec.min-financas.pt/NR/rdonlyres/DAA8DBD1-6B5D-4E98-A842-B3E880F83966/0/Circular_n_38_2011_II.pdf
http://www.dgaiec.min-financas.pt/NR/rdonlyres/F34AD282-21E0-4E05-9BDC-63D664661DCF/0/Circular_n_39_2011_II.pdf
http://www.dgaiec.min-financas.pt/NR/rdonlyres/F8AEAF06-CFAD-44E6-967E-B43F124A06CE/0/Circular_n_40_2011_II.pdf
