1. D. Bleecker, G. Csordas, Basic Partial Differential Equations (Chapman and Hall, New York, 1995)
2. L. Lam, Nonlinear Physics for Beginners (World Scientific, Singapore, 1998)
3. J.D. Logan, An Introduction to Nonlinear Partial Differential Equations (John Wiley, New York, 1994)
4. A.M. Wazwaz, Partial Differential Equations: Methods and Applications (Balkema, Leiden, 2002)
5. S. Kakei, N. Sasa, J. Satsuma, J. Phys. Soc. Jpn. 64, 1519 (1995)