Fonte:
http://www.dgaiec.min-financas.pt/NR/rdonlyres/6FEFC8BD-5874-4AD5-B733-0AD30421E3C0/0/Circular_n_119_2008_II.pdf
http://www.dgaiec.min-financas.pt/NR/rdonlyres/9B0A610B-0C6B-4CBD-A94D-3BB27A1BDD28/0/Circular_n_120_2008_II.pdf
http://www.dgaiec.min-financas.pt/NR/rdonlyres/1B933C60-EEB1-4853-88B0-76EEC29CD382/0/Circular_n_121_2008_II.pdf
