Owen, R. (1980). Countdown to english: An intermediate course for examinations. BBC.
Citazione stile Chigago Style (17a edizione)Owen, Roger. Countdown to English: An Intermediate Course for Examinations. Londres: BBC, 1980.
Citatione MLA (9a ed.)Owen, Roger. Countdown to English: An Intermediate Course for Examinations. BBC, 1980.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.