See also:
- ANACOM's Notice published in Diário da República no. 109/2004 (III Series), of May, 10 https://www.anacom.pt/render.jsp?categoryId=112179
- Statement on PT Comunicações, S.A.’s 2001 cost accounting system for the Fixed Telephone Service and the Leased Lines Service https://www.anacom.pt/render.jsp?categoryId=217184