1. H.K. Onnes, Akad. van Wetenschappen 14, 113 (1911)
2. Y.-X. Zhao, S. He, Solid State Commun. 45, 281 (1983)
3. L.E. Toth, Transition Metal Carbides and Nitrides (Academic Press, New York, 1971)
4. J.K. Hulm, R.D. Blaugher, AIP Conf. Proc. 4, 1 (1972)
5. K.S. Keskar, T. Yamashita, Y. Onodera, Jpn. J. Appl. Phys. 10, 370 (1971)