1. US Patent 1 740 351, published December 17, 1929.
2. RU Patent 2 169 606, published June 27, 2001.
3. Aristov, Yu.I., Kataliz Prom-sti, 2004, no. 6, p. 37.
4. RU Patent 2 274 484, published April 20, 2006.
5. RU Patent 2 214 304, published October 20, 2003.