· SPANISH NATIONAL TAX AUTHORITY
www.aeat.es

· BISCAY PROVINCIAL TAX AUTHORITY
http://www.bizkaia.net/home2/Temas/DetalleTema.asp?Tem_Codigo=2121

· GIPUZKOA PROVINCIAL TAX AUTHORITY
www4.gipuzkoa.net/ogasuna/normativa/

· ALAVA PROVINCIAL TAX AUTHORITY
http://web.alava.net/fiscal/nforales/

· DEPARTMENT OF ENERGY POLICY AND MINES (MINISTRY OF INDUSTRY, TOURISM AND COMMERCE)
http://www.mityc.es/Petroleo

· ACIEP (SPANISH ASSOCIATION OF PETROLEUM EXPLORATION AND PRODUCTION COMPANIES): A non-profit organisation with the objective of representing, managing and defending the interests of its members, real and intellectual, in relation to their activities in the exploration, production and subsurface storage at hydrocarbons. Secretary: Mr. Fernando Martín Esteban (fmareste@gmail.com)