United States. Postmaster General. (1931). Rules for sale of stamped envelopes, effective Jan. 2, 1932. U.S. GPO.
Chicago Style (17th ed.) CitationUnited States. Postmaster General. Rules for Sale of Stamped Envelopes, Effective Jan. 2, 1932. Washington: U.S. GPO, 1931.
MLA (9th ed.) CitationUnited States. Postmaster General. Rules for Sale of Stamped Envelopes, Effective Jan. 2, 1932. U.S. GPO, 1931.
Warning: These citations may not always be 100% accurate.