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In Print Publishing, 1996
Buku Teks
Shaplen, Robert, author
Harper & Row, 1965
Buku Teks
Council for Research in Values and Philosophy, 2006
Buku Teks
Taylor, Keith Weller.
University of California Press, 1983
Buku Teks
Jajasan Kebudajaan Sabar, 1965
Buku Teks