Savage, Christopher I., author
Hutchinson, 1975
Buku Teks
Speight, H., author
Macmillan, 1970
Buku Teks
edited by Kristian S. Palda
Prentice-Hall, 1973
Buku Teks
Stokes, Charles J., author
Random House, 1969
Buku Teks
Leavitt, Harold J., author
University of Chicago Press, 1958
Buku Teks