Fonte:
http://www.dgaiec.min-financas.pt/NR/rdonlyres/A6490DAB-6940-4F5B-9A61-ED2B599512B8/0/Circular_n_99_2009_II.pdf
http://www.dgaiec.min-financas.pt/NR/rdonlyres/0AFCBC95-F69B-4CF5-833C-844ED4DB2067/0/Circular_n_98_2009_II.pdf
