Fonte:
http://www.dgaiec.min-financas.pt/NR/rdonlyres/7D1EAE63-5F76-4F07-95D6-94D089318295/0/Circular_n_87_2008_II.pdf
http://www.dgaiec.min-financas.pt/NR/rdonlyres/601AD850-29C4-4EFD-A2E8-FD469F8DF7B9/0/Circular_n_88_2008_II.pdf
http://www.dgaiec.min-financas.pt/NR/rdonlyres/A7756DE4-619A-4A93-AA8E-91485D332F41/0/Circular_n_89_2008_II.pdf
