United States. Postmaster General. (1932). Cost ascertainment: Instruction letter B-a; record of parcel post by zone, weight, and size separations. U.S. GPO.
Chicago Style (17th ed.) CitationUnited States. Postmaster General. Cost Ascertainment: Instruction Letter B-a; Record of Parcel Post by Zone, Weight, and Size Separations. Washington: U.S. GPO, 1932.
MLA (9th ed.) CitationUnited States. Postmaster General. Cost Ascertainment: Instruction Letter B-a; Record of Parcel Post by Zone, Weight, and Size Separations. U.S. GPO, 1932.
Warning: These citations may not always be 100% accurate.