1. N. W. Bazley and M. Reeken,Lower bounds for critical values, Applicable Analysis, Vol.3, 209?211 (1973).
2. N. W. Bazley,Approximation of operators with reproducing nonlinearities, Manuscripta Math.18, 353?369 (1976).
3. F. Oberhettinger,Fourier expansion, a collection of formulas, Academic Press New York and London 1973.
4. S. Rosenblat,Asymptotic methods for bifurcation and stability problems, Mathematic Research Report, University of Melbourne, No. 10 (1978).
5. P. Rutkowski, Diplomarbeit, Universität zu Köln, 1979.