Parker, David, author
Cambridge University Press, 2011
eBooks
Edited by Donald earl childress III
Cambridge University Press, 2014
Buku Teks
Donaldson, Thomas, author
Oxford University Press, 1989
Buku Teks
Pojman, Louis P., author
Wadsworth and Cengage Learning, 2012
Buku Teks
Cambridge University Press, 1994
eBooks