Rescher, Nicholas
State University of New York Press, 2003
Buku Teks
Dicker, Georges
Oxford University Press , 2004
Buku Teks
Audi, Robert
Routledge, 2011
Buku Teks
Morton, Adam
Blackwell, 1997
Buku Teks
Chisholm, Roderick M.
Prentice Hall International, 1989
Buku Teks