1. A. N. Zelikman, B. G. Korshunov, A. V. Elyutin, and A. M. Zakharov, Niobium and Tantalum [in Russian], Metallurgiya, Moscow (1990).
2. Ya. Goroshchenko, Chemistry of Niobium and Tantalum [in Russian], Naukova Dumka, Kiev (1965).
3. N. P. Lyakishev, Yu. L. Pliner, and E. A. Rubenshtein, Niobium in Ferrous Metallurgy [in Russian], Metallurgiya, (1971).
4. Yu. S. Afonin, M. M. Veselkov, A. V. Uslamin, V. V. Shvydenko, N. V. Rodchenkov, and E. V. Il’enko, RF Patent 2245384 C22B 5/04. Claim 05.20.2003. Publ. 0.272005, Bull. No. 3.
5. V. I. Svechnikov, V. M. Pan, and V. I. Latyxheva, “Composition diagrams of the Nb-Al system,” Metallofizika, No. 22, 54–61 (29168)