1. A. R. Bishop, J. A. Krumhansl and S. E. Trullinger, Physica D 1, 1 (1980).
2. “Nonlinear Problems” Present and Future,” Eds. A. R. Bishop, D. K. Campbell and B. Nicolaenko, North-Holland, Mathematics Studies 61(1982).
3. G. L. Lamb, Jr., “Elements of Soliton Theory,” Wiley Interscience (1980).
4. “Solitons,” Eds. R. K. Bullough and P. J. Caudrey, Springer-Verlag (1980).
5. R. K. Dodd, et. al., “Solitons and Nonlinear Wave Equations,” Academic Press (1983).