(NmR(B-(NGRUPPY (B/s - (N{UNKOW(B, (NwLADIMIR pETROWI^s ((NmOSKWA (B:s (NnAUKA(B,s, 1990)
(NbIBLIOGR(B.: (NS(B. 157-158s
Keywords: (NgRUPPY (B((NMAT(B.) (NKONE^NYEs