Helgesen, M., Brown, S., & Smith, D. (1999). Active listening: Expanding understanding through content : Level 3 [Đĩa CD-ROM]. Cambridge: Cambridge University Press.
Trích dẫn kiểu ChicagoHelgesen, Marc, Steven Brown, và Dorolyn Smith. Active Listening: Expanding Understanding Through Content : Level 3 [Đĩa CD-ROM]. Cambridge: Cambridge University Press, 1999.
Deismireacht MLAHelgesen, Marc, Steven Brown, và Dorolyn Smith. Active Listening: Expanding Understanding Through Content : Level 3 [Đĩa CD-ROM]. Cambridge: Cambridge University Press, 1999.
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