Gregory, Robert Henry, author
Wadsworth, 1963
Buku Teks
Burian, Barbara J., author
Prentice-Hall, 1982
Buku Teks
Gregory, Robert Henry, author
Chatto and Windus, 1963
Buku Teks
Awad, Elias M., author
Prentice-Hall, 1971
Buku Teks
Carter, Norman H., author
Dickenson , [s.a.]
Buku Teks