Cita APA (7th ed.)

Crystal, D., & Davy, D. (1975). Advanced conversational english. Longman Group.

Cita Chicago (17th ed.)

Crystal, David, i Derek Davy. Advanced Conversational English. Londres: Longman Group, 1975.

Cita MLA (9th ed.)

Crystal, David, i Derek Davy. Advanced Conversational English. Longman Group, 1975.