APA (7th ed.) Citation

United States. Post Office Department. (1927). Precanceled stamps on 1st-class matter. GPO.

Chicago Style (17th ed.) Citation

United States. Post Office Department. Precanceled Stamps on 1st-class Matter. [Washington]: GPO, 1927.

MLA (9th ed.) Citation

United States. Post Office Department. Precanceled Stamps on 1st-class Matter. GPO, 1927.

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