1. EEC. Council-Regulation (EEC) No. 1836/93 of 29. June 1993 allowing voluntary participation by companies in the industrial sector in a Community Eco-management and audit scheme, EMAS-Regulation. Brussels: EEC, 1993.
2. Environmental management systems;International Standard Organisation,1995
3. Environmental performance evaluation;International Standard Organisation,1998
4. Leitfaden Umweltberichte für die Öffentlichkeit. Germany: Deutsches Institut für Normung, 1997. DIN 33922.
5. Guidelines for corporate sustainability reporting;Global Reporting Initiative (GRI),1999