Brym, Robert J., author
Wadsworth and Cengage Learning, 2013
Buku Teks
Jacobs, Kristof, author
Palgrave Macmillan, 2016
Buku Teks
Barker, Ernest, author
Clarendon Press, 1952
Buku Teks
Schroeder, John Frederick, author
The Mount Vernon Ladies Association, 1947
Buku Teks
McRobert, Kenneth
McClelland and stewart, 1976
Buku Teks