Cita APA (7a ed.)

Ek, J. A. v., & Alexander, L. G. (1982). Threshold level Englihs in an European unit-credit system for modern language learning by adults. Pergamon.

Cita Chicago Style (17a ed.)

Ek, Jan Ate van, y L. G. Alexander. Threshold Level Englihs in an European Unit-credit System for Modern Language Learning by Adults. Oxford [etc.]: Pergamon, 1982.

Cita MLA (9a ed.)

Ek, Jan Ate van, y L. G. Alexander. Threshold Level Englihs in an European Unit-credit System for Modern Language Learning by Adults. Pergamon, 1982.