APA

O'Connell S., . (2000). Proficiency. Harlow: Longman.

Chicago

O'Connell S, . 2000. Proficiency. Harlow: Longman.

Harvard

O'Connell S., . (2000). Proficiency. Harlow: Longman.

MLA

O'Connell S, . Proficiency. Harlow: Longman. 2000.