1. B.H. Engler, J. Leyrer, E.S. Lox and K. Ostgathe, SAE930735, Detroit MI, 1?5 March 1993.
2. D.R. Monroe, C.L. DiMaggio, D.D. Beck and F.A. Matekunas, SAE930737, Detroit MI, 1?5 March 1993.
3. M. Kunno, T. Chikahisa, T. Murayama and M. Iwamoto, SAE Meeting, Detroit MI, 24?28 February 1992.
4. M. Iwamoto, N. Mizuno and H. Yahiro, Sekiyu Gakkaishi 34 (1991) 375.
5. M. Iwamoto, H. Yahiro, S. Shundo, Y. Yu-u and N. Mizuno, Appl. Catal. 69 (1991) L15.