Citazione APA

An Official TOEFL Study Aid. (1989). Understanding TOEFL: Workbook. USA: Educational Testing Service.

Stile di citazione Chicago

An Official TOEFL Study Aid. Understanding TOEFL: Workbook. USA: Educational Testing Service, 1989.

Citazione MLA

An Official TOEFL Study Aid. Understanding TOEFL: Workbook. USA: Educational Testing Service, 1989.

Attenzione: Queste citazioni potrebbero non essere precise al 100%.