. . "Cherkasov, N. A. (Nikolaĭ Aleksandrovich)" . "N. A. CHERKASOV" . . "Н. А. Черкасов" . "CHERKASOV" . "A."@en . "Cherkasov"@en . "Nikolaĭ Aleksandrovich Cherkasov" . "N. A. Cherkasov"@en . "Aleksandrovich" . "N."@en . . "Черкасов" . "Н." . . "А." . "Nikolaĭ" . .