1. P. Zelenka, W. Kriegler, P. Herzog, W. Cartellieri: SAE 900602 (1990).
2. K. Voss, J. Lampert, R. Farrauto, G. Rice, A. Punke, R. Krone:Third International Congress on Catalysis and Automotive Pollution Control, April 20–22, 1994, Brussels, Belgium.
3. R. Beckmann, W. Engeler, E. Mueller, B. Engler, L. Leyrer, E. Lox, K. Ostgathe: SAE 922330 (1992).
4. D. Domesle, B. Engler, E. Koberstein, H. Voelker: U.S. Patent 5, 157,007.
5. M. Wyatt, W. Manning, S. Roth, M. D’Aniello, Jr., E. Andersson, S. Fredholm: SAE 930130 (1993).