1. Groot, S.R. De, Mazur, P.: Non equilibrium thermodynamics. Amsterdam: North Holland 1962
2. Graham, R. Haken, H.: Z. Physik243, 289 (1971);245, 141 (1971)
3. Risken, H.: Z. Physik251, 231 (1972)
4. Graham, R.: Springer Tracts in Modern Physics. Vol. 66. Berlin, Heidelberg, New York: Springer 1973
5. Abramowitz, M., Stegun, I.: Handbook of Mathematical Functions. Dover, New York: 1965