Cita APA (7th ed.)

Obee, B. (1998). Cambridge first certificate: Grammar and usage. Cambridge University Press.

Cita Chicago (17th ed.)

Obee, Bob. Cambridge First Certificate: Grammar and Usage. Cambridge: Cambridge University Press, 1998.

Cita MLA (8th ed.)

Obee, Bob. Cambridge First Certificate: Grammar and Usage. Cambridge University Press, 1998.