Fonte:
http://www.dgaiec.min-financas.pt/NR/rdonlyres/53A04679-154E-4FA1-8CD1-97E6D984CE3B/0/Circular_n_100_2008_II.pdf
http://www.dgaiec.min-financas.pt/NR/rdonlyres/3EBBADD0-38A4-4446-9E34-237D36199EE7/0/Circular_n_101_2008_II.pdf
http://www.dgaiec.min-financas.pt/NR/rdonlyres/8D6B48B2-4840-4D6B-A38D-3692B33A73A9/0/Circular_n_102_2008_II.pdf
