Fonte:
http://www.dgaiec.min-financas.pt/NR/rdonlyres/CD5993D5-B105-4ECF-93FF-8E4DCF49DAD0/0/Circular_n_106_II.pdf
http://www.dgaiec.min-financas.pt/NR/rdonlyres/C9C8D8C8-775D-4336-84E4-8ECD87DE3B51/0/Circular_n_107_II.pdf
http://www.dgaiec.min-financas.pt/NR/rdonlyres/808B05FB-2E86-4F7C-B6D9-583C4E73BADA/0/Circular_n_108_2008_II.pdf
http://www.dgaiec.min-financas.pt/NR/rdonlyres/760E776B-805F-4D24-B94F-D71A438BD6F8/0/Circular_n_109_2008_II.pdf
