Allyn and Bacon, 1990
Buku Teks
Tompkins, Teri C.
Prentice-Hall, 2002
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Jonathan Proklamanto, author
Fakultas Ekonomi dan Bisnis Universitas Indonesia, 2014
UI - Skripsi (Membership)
Knudson, Harry R., author
Winthrop, 1978
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Cummings, L.L., author
Richard D. Irwin, 1980
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