APA (7th ed.) Citation

United States. Postmaster General. (1929). Changes in prices of stamped envelopes. U.S. GPO.

Chicago Style (17th ed.) Citation

United States. Postmaster General. Changes in Prices of Stamped Envelopes. Washington: U.S. GPO, 1929.

MLA (9th ed.) Citation

United States. Postmaster General. Changes in Prices of Stamped Envelopes. U.S. GPO, 1929.

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