(1968). United States government correspondence manual. U.S. Government Printing Office.
Dyfyniad Arddull ChicagoUnited States Government Correspondence Manual. Washington: U.S. Government Printing Office, 1968.
Dyfyniad MLAUnited States Government Correspondence Manual. U.S. Government Printing Office, 1968.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.