(NlEKCII PO WARIACIONNOMU IS^ISLENI@ (B/s - (NbLISS(B, (NdVILBERT a(B.s; (NsOLNCEW(B, (N`(B.s ((NmOSKWA (B:s (NiZD(B-(NWO INOSTR(B. (NLIT(B., s, 1950)
Keywords: (NwARIACIONNOE IS^ISLENIEs