Buckley, Roger, author
Cambridge University Press, 1990
Buku Teks
International Society for Educational Information, 1989
Buku Teks
Woolf, Emile, author
Prentice-Hall, 1986
Buku Teks
Oliver, Gordon, author
Prentice-Hall, 1980
Buku Teks
Miller, Roger LeRoy, author
Pearson education, 2010
Buku Teks