Keen, Jeffrey S.
John Wiley & Sons, 1981
Buku Teks
Wooldridge, Susan, author
Auerbach, 1973
Buku Teks
Lyon, John K., author
John Wiley & Sons, 1976
Buku Teks
Grindley, Kit, author
Pustaka Binaman Pressindo, 1985
Buku Teks
Waters, S. J., author
NCC Publications, 1979
Buku Teks