Berstein Israel

Publications in Math-Net.Ru

1. On co-groups in the category of graded algebras
   
   Matematika, 10:4 (1966),  32–44
2. On the problem of periodical solutions of non-linear systems with a small parameter
   
   Dokl. Akad. Nauk SSSR, 113:1 (1957),  9–11