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Majalah, Jurnal, Buletin
Palmer, James O., author
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Buku Teks
Kaplan, Robert M., author
Wadsworth and Cengage Learning, 2013
Buku Teks
edited by Curtiss P. Hansen and Kelley A. Conrad
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Buku Referensi
Cohen, Ronald Jay, author
McGraw-Hill, 2005
Buku Teks