1. Council Directive of 21 May 1991 concerning Urban Waste-Water Treatment (91/271/EEC).
2. Directive 2000/60/EC of the European Parliament and of the Council, of 23 October 2000, establishing a framework action in the field of water policy.
3. USEPA, Process design manual, Wastewater treatment facilities for sewered small communities, 1997.
4. J.J. Salas, Tecnologías de depuración, Situación actual y perspectivas, IV Congrés Ibéric de gestió i Planificació de l'Aigua, 8–12 diciembre 2004, Tortosa-Spain, 2004.
5. Andalusian Regional Ministry of Public Works and Transport, Experimental Plant of Wastewater Depuration, Evolution and Experience, 1997.