1. On the oscillation of solutions of some ordinary differential equations. Sov. Math. Dokl. 3, 649-652 (1962)
2. On oscillation conditions for solutions of the equation u ″ + a ( t ) | u | n sign u = 0 . Čas. Pěst. Mat. 87(4), 492-495 (1962) (in Russian)
3. On asymptotic properties of solutions of the equation u ″ + a ( t ) | u | n sign u = 0 . Soobshch. Akad. Nauk Gruz. SSR 30(2), 129-136 (1963) (in Russian)
4. On the oscillation of solutions of the equation d m u / d t m + a ( t ) | u | n sign u = 0 . Mat. Sb. 65(2), 172-187 (1964) (in Russian)
5. On the asymptotic representation of solutions of linear differential equations. Tr. Tbilis. Univ. Mat. Mekh. Astron. 102, 149-167 (1964) (in Russian)