Cita APA (7a ed.)

Jespersen, O., & Yhlen-Olsen Bertelsen, S. (1967). How to teach a foreign language (13th impression.). George Allen & Unwin.

Cita Chicago Style (17a ed.)

Jespersen, Otto, y Sophia Yhlen-Olsen Bertelsen. How to Teach a Foreign Language. 13th impression. London: George Allen & Unwin, 1967.

Cita MLA (9a ed.)

Jespersen, Otto, y Sophia Yhlen-Olsen Bertelsen. How to Teach a Foreign Language. 13th impression. George Allen & Unwin, 1967.