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.
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