Allen, H. B., & Campbell, R. N. (1972). Teaching English as a Second Language (2nd ed.). McGraw-Hill.
Παραπομπή Chicago StyleAllen, Harold B., και Russell N. Campbell. Teaching English as a Second Language. 2nd ed. Bombay: McGraw-Hill, 1972.
Παραπομπή MLAAllen, Harold B., και Russell N. Campbell. Teaching English as a Second Language. 2nd ed. McGraw-Hill, 1972.
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