Roth, Mitchel P., author
Cengage Learning , 2010
Buku Teks
Baker, Thomas E., author
Pearson - Prentice Hall, 2005
Buku Teks
Sheley, Joseph F., author
Wadsworth, 1987
Buku Teks
edited by Diane Richardson
Open University Press, 1996
Buku Teks
Johnson, Paul, author
Routledge, 2005
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