1. 1) Segal, V. M., Reznikov, V. I., Drobyshevskiy, A. E. & Kopylov, V. I. :Russian Metall., 1(1981), 99.
2. 2) Bridgman, P. W. :Studies in Large Plastic Flow and Fracture,(1952), McGraw-Hill, New York, NY.
3. 3) Iwahashi, Y., Wang, J., Horita, Z., Nemoto, M. & Langdon, T. G. :Scripta Mater., 35(1996), 143.
4. 4) Valiev, R. Z., Estrin, Y., Horita, Z., Langdon, T. G., Zehetbauer, M. J. & Zhu, Y. T. :JOM, 58-4(2006), 33.
5. 5) Senkov, O. N., Froes, F. H., Stolyarov, V. V., Valiev, R. Z. & Liu, J. :Nanostruct Mater., 10(1998), 691.