Lawlor, Steven C., author
Harcourt Brace Jovanovich, 1992
Buku Teks
Page, E. S., author
Cambridge University Press, 1976
Buku Teks
McLeod, Raymond, author
Macmillan, 1993
Buku Teks
McLeod, Raymond, author
Prentice-Hall, 1995
Buku Teks
McLeod, Raymond, author
Macmillan, 1990
Buku Teks