1. M.J. ABLOWITZ, D.J. KAUP, A.C. NEWELL, AND H. SEGUR, The inverse scattering transform-Fourier analysis for nonlinear problems, Studies in Appl. Math. 53 (1974), 249–315.
2. V.I. ARNOLD AND A.A. AVEZ, Ergodic Problems of Classical Mechanics, W.A. Benjamin, Inc., New York, New York, 1968.
3. Y.A. BEREZIN AND V.I. KARPMAN, Nonlinear evolution of disturbances in plasmas and other dispersive media, Soviet Physics JETP 24 (1967), 1049–1056.
4. K.M. CASE AND S.C. CHIU, The discrete version of the Marchenko equations in the inverse scattering problem, Rockefeller Univ. Report (1974).
5. R. DECK, F. HOPF, AND G.L. LAMB, JR., Univ. of Arizona, preprint (1975).