Fonte:
http://www.dgaiec.min-financas.pt/NR/rdonlyres/0893A07E-D10B-4CA9-BF53-9D8CFDA7475B/0/Circular_n_35_2011_II.pdf
http://www.dgaiec.min-financas.pt/NR/rdonlyres/1423CA49-F982-47D8-B885-9A350C45B405/0/Circular_n_36_2011_II.pdf
