1. WBCSD (World Business Council for Sustainable Development). Eco-efficiency: creating more value with less impact. Geneva; 2000.
2. WCED (World Commission on Environment and Development). Brundtland report on our common future. United Nations; 1987.
3. Kharel GP. Evaluation of eco-efficiency of iron and steel industries in Nepal, A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science (Industrial Ecology and Environment) Faculty of Environment and Resource Studies. Copyright of Mahidol University; 2006.
4. Calculating eco-efficiency indicators: a workbook for industry;NRTEE (National Round Table on the Environment and the Economy),2001