Jim Dugger. (1992). Business letters for busy people. Golden Books Centre.
Cita Chicago (17th ed.)Jim Dugger. Business Letters for Busy People. Kuala Lumpur: Golden Books Centre, 1992.
Cita MLA (8th ed.)Jim Dugger. Business Letters for Busy People. Golden Books Centre, 1992.
Atenció: Aquestes cites poden no estar 100% correctes.