Fonte:
http://www.dgaiec.min-financas.pt/NR/rdonlyres/0634656B-2FB3-4346-BFE9-0DFB5ACA9F73/0/Circular_n_123_2009_II.pdf
http://www.dgaiec.min-financas.pt/NR/rdonlyres/AAA0D397-627A-4157-838C-781F198D8931/0/Circular_n_122_2009_II.pdf
