APA (7th ed.) Citation

United States. Post Office Department. (1928). Postal Union transit statistics (May 1-May 28, inclusive, 1929). GPO.

Chicago Style (17th ed.) Citation

United States. Post Office Department. Postal Union Transit Statistics (May 1-May 28, Inclusive, 1929). [Washington]: GPO, 1928.

MLA (9th ed.) Citation

United States. Post Office Department. Postal Union Transit Statistics (May 1-May 28, Inclusive, 1929). GPO, 1928.

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