Fonte:
http://www.dgaiec.min-financas.pt/NR/rdonlyres/ED447666-8EB5-4A11-8E5B-BDCB77756549/0/Circular__n_45_2011_II.pdf
http://www.dgaiec.min-financas.pt/NR/rdonlyres/B153DEE9-2C0B-4153-BEE0-7305A6ED0885/0/Circular_n_46_2011_II.pdf
http://www.dgaiec.min-financas.pt/NR/rdonlyres/5DFEAA7E-35D8-41E2-8853-F1A441A2EA71/0/Circular_n_47_2011_II.pdf
