editor, Gerald P. Koocher, John C. Norcross, Sam S. Hill
Oxford University Press, 2005
Buku Referensi
New-York: Prentice Hall, 1993,
Buku Referensi
Heisler, Sanford I, author
John Wiley & Sons, 1984
Buku Referensi
editors, Gerald P. Koocher, John C. Norcross, Sam S. Hill, III.
Oxford University Press, 2005
Buku Teks
Wilcocks, Julie, author
Clive Bincley, 1985
Buku Referensi