Ayer, A. J. (Alfred Jules), 1910-1989, author
Penguin Books, 1956
Buku Teks
Chisholm, Roderick M., author
Prentice Hall International, 1989
Buku Teks
Wojciechowski, Jerzy A., author
Council for research in values and philosophy, [Date of publication not identified]
Buku Teks
McCarthy, E. Doyle, author
Routledge, 1996
Buku Teks
Thurow, Lester C., author
HarperCollins, 1999
Buku Teks