Kendall, Diana
Wadsworth, 2013
Buku Teks
Kendall, Diana
Wadsworth/Thomson learning, 2000
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Kendall, Diana
Cengage Learning, 2017
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Orum, Anthony M.
Rowman & Littlefield Publishers, 1999
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Schrag, Clarence C.
Harper & Row, 1963
Buku Teks