1. Yu.F. Rybkin, B.G. Zaslavsky, Yu.A. Solomaha, USSR Patent No. 374901, C30 B11/00, 1971.
2. Yu.M. Karpov, USSR Patent No. 1248330 A, 1984.
3. Yu.M. Karpov, V.R. Lubinsky, USSR Patent No. 1401931, 1985.
4. A.G. Ostrogorsky, US Patent Application S, No. 397741, 1989.
5. V.D. Golyshev, M.A. Gonik, Russian Patent No. 1800854, 1990.