APA (7th ed.) Citation

United States. Patent and Trademark Office. (1997). Classification main menu. U.S. Patent and Trademark Office.

Chicago Style (17th ed.) Citation

United States. Patent and Trademark Office. Classification Main Menu. Washington, D.C.: U.S. Patent and Trademark Office, 1997.

MLA (9th ed.) Citation

United States. Patent and Trademark Office. Classification Main Menu. U.S. Patent and Trademark Office, 1997.

Warning: These citations may not always be 100% accurate.