1. M. Boiti andF. Pempinelli:Nuovo Cimento B,59, 40 (1980).
2. Nonlinear evolution equations and dynamical systems, inLecture Notes in Physics, No. 120, edited byM. Boiti, F. Pempinelli andG. Soliani (Berlin, 1980).
3. Solitons, inTopics in Current Physics, No. 17, edited byR. K. Bullough andP. J. Caudrey (Berlin, 1980).
4. M. Boiti andF. Pempinelli:Nuovo Cimento B,51, 70 (1979).
5. M. Boiti andF. Pempinelli:Nuovo Cimento B,56, 148 (1980).