1. Discussions with G. Deleens.
2. G. Deleens Ph.D Thesis Rouen (1975).
3. G. Deleens, P. Foy, E. Marechal, Eur Pol Journal Vol. 13, pp. 337–342, 343–351, 351–360 (1977).
4. G. Deleens, P. Foy, C. Jungblut French Patent 2,273, 021 (1974);
5. G. Deleens, P. Foy, U.S. Patent 4,230, 838 (1980);