1. S. Glasstone, K.J. Laidler, H. Eyring: The theory of Rate processes (McGraw-Hill, New York 1941)
2. D. Liotard: Int. J. Quant. Chem. Submitted for publication
3. M.S. Berger, M.S. Berger: Perspectives in Nonlinearity (Benjamin, New York 1968) th. 2.25 p. 59;
4. M.S. Berger: Nonlinearity and Functional Analysis (Academic New York 1977) th. 6.5.3 p. 354
5. A. Ambrosetti, P.H. Rabinowitz: J. Funct. Anal. 14, 349 (1973)