Ehrmann, Henry W., author
Prentice-Hall, 1976
Buku Teks
David, Rene, 1906-, author
Stevens & sons, 1985
Buku Teks
Gutteridge, H. C.
Cambridge University Press, 1949
Buku Teks
Glendon, Mary Ann
ST. Paull Minn, 1999
Buku Teks
Orucu, A. Esin, author
Inaugural Lecture, 1982
Buku Teks