Levin, Anatoliĭ: Факторизация и непонижение осцилляции на окружности.
(Russian) [Factorization and nonlowering of oscillations at the boundary].
In:
Greguš, Michal (ed.): Equadiff 5.
Proceedings of the Fifth Czechoslovak Conference on Differential Equations and Their Applications held in Bratislava, August 24-28, 1981.
BSB B.G. Teubner Verlagsgesellschaft, Leipzig, 1982.
pp. 226-227
