Cita APA (7a ed.)

Ridley, J. R. (1990). Safety at work (Third edition.). Butterworth-Heinemann.

Cita Chicago Style (17a ed.)

Ridley, John R. Safety at Work. Third edition. London ; Boston: Butterworth-Heinemann, 1990.

Cita MLA (8a ed.)

Ridley, John R. Safety at Work. Third edition. Butterworth-Heinemann, 1990.