APA aipamena

Duckworth, M., & Gude, K. (2000). Countdown to first certificate: Student's book (6th ed.). Oxford: Oxford U. P..

Chicago Style aipamena

Duckworth, Michael, và Kathy Gude. Countdown to First Certificate: Student's Book. 6th ed. Oxford: Oxford U. P., 2000.

MLA aipamena

Duckworth, Michael, và Kathy Gude. Countdown to First Certificate: Student's Book. 6th ed. Oxford: Oxford U. P., 2000.