1. I. Gumowski, Proc. 1st IFAC Congress on Sensitivity Analysis, Dubrovnik, 1964 (Pergamon Press, Inc., Oxford, 1966).
2. Proc. 5th Int. Congress on Non-Linear Oscillations, Kiev, 1969. (Ukrainian SSSR Acad. Sci., 1969.)
3. Oscillation of quasi-linear systems with delay;Rubanik,1969
4. Methods of averaging in differential and integro-differential equations;Filatov,1971
5. New qualitative methods in celestial mechanics;Grebenikov,1971