Crews, F. C. (1994). Speaking effectively: Developing speaking skills for business English. Cambridge University Press.
Lua i Stíl Chicago (17ú heag.)Crews, Frederick C. Speaking Effectively: Developing Speaking Skills for Business English. Cambridge: Cambridge University Press, 1994.
Lua MLA (8ú heag.)Crews, Frederick C. Speaking Effectively: Developing Speaking Skills for Business English. Cambridge University Press, 1994.
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