Stumpf, Samuel Enoch, 1918-1998, author
McGraw-Hill, 1989
Buku Teks
Russell, Bertrand, 1872-1970, author
Oxford University Press, 1912
Buku Teks
Buku Teks
edited by John K. Ryan
The Catholic University of America Press, 1963
Buku Teks
Rachels, James, 1941-2003, author
McGraw-Hill, 2012
Buku Teks