Mike jenks, Colin jones
Springer, 2010
Buku Teks
Wick, Robert J., author
Oxford University Press, 2007
Buku Teks
Richard T. LeGates, Frederic Stout, editor
Routledge, 2000
Buku Teks
Konrad Otto-Zimmermann, editor
Springer, 2012
Buku Teks
Hartshorn, Truman Asa, author
John Wiley & Sons, 1980
Buku Teks