Tupas, T. R. F. (2002). Second language teaching. University of the Philippines Open University.
Chicago-viite (17. p.)Tupas, T. Ruanni F. Second Language Teaching. Quezon City: University of the Philippines Open University, 2002.
MLA-viite (9. p.)Tupas, T. Ruanni F. Second Language Teaching. University of the Philippines Open University, 2002.
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