(N~TO TAKOE DIFFERENCIROWANIE(B? /s - (NbOLTQNSKIJ(B, (NwLADIMIR gRIGORXEWI^s ((NmOSKWA (B:s (NfIZMATGIZ(B,s, 1960)
Keywords: (NdIFFERENCIALXNOE IS^ISLENIEs