Koehler, James O. "Organo-Zirconium Derivatives." U. S. Patent number: 2978347. Washington, DC: United States Patent and Trademark Office, 1961. http://www.uspto.gov/patft/index.html (15 November 2007).

Koehler, James O. "Organo-Zirconium Derivatives." U. S. Patent number: 2978347. Washington, DC: United States Patent and Trademark Office, 1961. http://www.uspto.gov/patft/index.html (15 November 2007).