Dessler, Gary, 1942-, author
Prentice-Hall, 1980
Buku Teks
Brown, Warren B., author
John Wiley & Sons, 1980
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
Hatch, Mary Jo
Oxford University Press, 1997
Buku Teks