1. Perman, E. P. Proc. R. Soc. A76, 167–174 (1905).
2. Bosch, C., Mittasch, A., Stern, G. & Wolf, H. German Patents (DRP) 249, 447; 258, 146 (January 1910).
3. Mittash, A. Adv. Catal. 2, 81–104 (1950).
4. Nielsen, H. Catal. Rev. Sci. Engng 23, 17–51 (1981).
5. Timm, B. Proc. 8th int. Congr. Catal., Berlin Vol. 1, 7 (Verlag Chemie, Berlin, 1984).