Fonte:
http://www.dgaiec.min-financas.pt/NR/rdonlyres/AB229A05-7807-47FD-AC69-324348950F7F/0/Circular_n_60_2008_II.pdf
http://www.dgaiec.min-financas.pt/NR/rdonlyres/72FF43CF-52EF-449A-821F-9EAF0D5F3053/0/Circular_n_61_2008_II.pdf
http://www.dgaiec.min-financas.pt/NR/rdonlyres/5AA8A868-2FD4-47CB-9CC9-5FB4D9D54E3A/0/Circular_n_62_2008_II.pdf
