1. P.A. Akishin, O.T. Nikitin, and L.N. Gorohov: Dokl. AN SSSR, 1959, vol. 125, p. 1075 (in Russian).
2. W.A. Knarr: Ph.D. Thesis, University of Kansas, 1959.
3. C. Brosset and B. Magnusson: Nature, 1960, vol. 187, pp. 54–55.
4. G.V. Samsonov, L.Y. Markovskii, A.F. Jigach, and M.G. Valyashko: Boron, Its Compounds and Alloys, Academy of Sciences, Ukrainian SSR, 1960.
5. G.V. Samsonov and V.M. Sleptsov: Dopovidi Akad. Nauk Ukr. RSR, 1962, vol. 8, p. 1066 (in Ukrainian).