Lewis, John P.
Addison-Wesley, 1999
Buku Teks
Tennant, Kylie
Macmillan, [Date of publication not identified]
Buku Teks
Arnaud, A. A.
Woodhead-Faulkner, 1985
Buku Teks
Metcalf, Michael
Oxford University Press , 1990
Buku Teks
Mitchell, Mark L.
Wadsworth and Cengage Learning, 2013
Buku Teks