Fonte :
http://www.dgaiec.min-financas.pt/NR/rdonlyres/006ABABF-02A5-49FF-807C-FB2B90A9BBFA/0/Circular_n_74_2008_II.pdf
http://www.dgaiec.min-financas.pt/NR/rdonlyres/A91888B0-D4D5-4634-B5D5-A854B33757E1/0/Circular_n_76_2008_II.pdf
