Bakieva, A. Gulnara
Council for Research in Values and Philosophy, 2007
Buku Teks
edited by John P. Robinson, Phillip R. Shaver, Lawrence S. Wrightsman
Academic Press, 1991
Buku Teks
Lejeue, Philippe
University of Minnesota Press, 1989
Buku Teks
Irvington Publ., 1967
Buku Teks
Cambridge University Press, 1982
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