1. Feigl, F. (1949).Chemistry of Specific, Selective and Sensitive Reactions (Academic Press, New York), P. 251.
2. Hegetschweiler, H., Hancock, R., and Green, B. (1975). Private communication of unpublished results.
3. Saarinen, H., and Korvenranta, J. (1975).Acta Chem. Scand. A29, 409.