Kagan, V. F. (1944). Lobachevskiĭ.
Lua i Stíl Chicago (17ú heag.)Kagan, V. F. Lobachevskiĭ. Moskva, 1944.
Lua MLA (8ú heag.)Kagan, V. F. Lobachevskiĭ. 1944.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.
Kagan, V. F. (1944). Lobachevskiĭ.
Lua i Stíl Chicago (17ú heag.)Kagan, V. F. Lobachevskiĭ. Moskva, 1944.
Lua MLA (8ú heag.)Kagan, V. F. Lobachevskiĭ. 1944.