United States. Post Office Dept. (1968). National Zip code directory. [Bureau of Operation.
Chicagoスタイル(17版)引用形式United States. Post Office Dept. National Zip Code Directory. Washington: [Bureau of Operation, 1968.
MLA(9版)引用形式United States. Post Office Dept. National Zip Code Directory. [Bureau of Operation, 1968.
警告: この引用は必ずしも正確ではありません.