Staub, Dick, author
John Wiley & Sons Inc., 2007
Buku Teks
Hryniewicz, Waclaw
Council for Research in Values and Philosophy, 2007
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Winzeler, Robert L.
Buku Teks
Winzeler, Robert L.
Lanham Rowman & Littlefield, 2016
Buku Teks
Storey, John, 1950-, author
Prentice-Hall, 2000
Buku Teks