Cita APA (7a ed.)

Duckworth, M. (2009). At your Service Workbook. Oxford University.

Cita Chicago Style (17a ed.)

Duckworth, Michael. At Your Service Workbook. Reino Unido: Oxford University, 2009.

Cita MLA (8a ed.)

Duckworth, Michael. At Your Service Workbook. Oxford University, 2009.