Abadinsky, Howard, author
Prentice-Hall, 1979
Buku Teks
Burke, Gill, author
Longman, 1981
Buku Teks
Peffer, R.G. (Rodney G.), 1952-, author
Princeton University Press, 1990
Buku Teks
Viano, Emilio C., author
Nelson-Hall, 1975
Buku Teks
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