Norton, Alan
Cheltenham Edward Elgar , 1997
Buku Teks
Wang, James C.F., author
Prentice-Hall, 1994
Buku Teks
Greene, Thomas H., author
Prentice-Hall, 1984
Buku Teks
Hague, Rod., author
Palgrave Macmillan , 2013
Buku Teks
edited by Nimrod Raphaeli
Allyn and Bacon, 1967
Buku Teks