1. Braunschweig, A. (1993) Schweizerische Vereingung für ökilogisch bewusste Unternehmungsführung, personal communications, Im stieg 7, 8134 Adlisnil, Switzerland.
2. BUWAL, (1984) Oekobilanz von Packstoffenstand, Swiss Federal Office of environment, Forests, and Landscape, Berne, Switzerland.
3. Cohen Hubal, E. (1992) Net waste reduction analysis applied to air pollution control technologies and zero waste discharge systems. MS thesis. Dept. of Chemical Engineering, North Carolina State Univ. 103p.
4. Cohen Hubal, E. and M. Overcash (1993) Net waste reduction analysis applied to air pollution control technologies, J. Air and Waste Mgmt Assoc.43:1449–1454
5. Eyerer, P. (1993) personal communications, University of Stuttgard, Institute für Kunststoffprufung and Kunststoffkunde.