Cita APA (7a ed.)

Gethin, H. (1983). Grammar in context: Proficiency level English. Collins E.L.T.

Cita Chicago Style (17a ed.)

Gethin, Hugh. Grammar in Context: Proficiency Level English. London [etc.]: Collins E.L.T, 1983.

Cita MLA (9a ed.)

Gethin, Hugh. Grammar in Context: Proficiency Level English. Collins E.L.T, 1983.