1. R. Speiser, G.R. St. Pierre, in: N.E. Promisel (Ed.), The Science and Technology of Refractory Metals, Pergamon, New York, 1964, p. 289
2. High Temperature Oxidation of Metals;Kofstad,1966
3. H. Inouye, in: D.L. Douglass, R.W. King (Eds.), Columbium Metallurgy, Proc. Metall. Society AIME Conf., vol. 10, Interscience, New York, 1960