1. Du nombre de cycles limites naissant en cas de variation des coefficients d'un état d'équilibre du type foyer ou centre;Bautin;Dokl. Akad. Nauk SSSR,1939
2. On the number of limit cycles which appear with the variation of coefficients from an equilibrium position of focus or center type (R);Bautin;Mat. Sb.,1952
3. On periodic solutions of a system of differential equations (R);Bautin;Prikl. Mat. Meh.,1954
4. On conditions for the existence of a center (R);Belyustina;Prikl. Mat. Meh.,1954