Waldman, Don E., author
Pearson, 2007
Buku Teks
Woodward, Joan, author
Oxford University Press, 1965
Buku Teks
Hayes, Patrick, author
John Wiley & Sons, 1975
Buku Teks
Seckler-Hudson, Catheryn, author
Washington, D.C., The American University Press
Buku Teks
written by M. C. Barnes [and others]
Allen & Unwin, 1970
Buku Teks