United Nations Division for Sustainable Development (2001): "Environmental Management Accounting, Procedures and Principles", United Nations publication, Economic and Social Affairs Series, Internet: www.un.org/esa/sustdev/estema1.htm.
United Nations Division for Sustainable Development (2001): "Environmental Management Accounting, Procedures and Principles", United Nations publication, Economic and Social Affairs Series, Internet: www.un.org/esa/sustdev/estema1.htm (Vereinte Nationen, Abteilung für nachhaltige Entwicklung: Umweltrechnungswesen - Grundsätze und Vorgehensweise).