Fonte:
http://www.dgaiec.min-financas.pt/NR/rdonlyres/6FBBF396-2AFA-4D68-84EE-4B533581359A/0/Circular_n_11_2009_II.pdf
http://www.dgaiec.min-financas.pt/NR/rdonlyres/4A41AA2C-9399-46DE-AF30-E2C163D164D7/0/Circular_n_12_2009_II.pdf
