Hoek, C. van den
Cambridge University Press, 2002
Buku Teks
Sharma, O.P., 1953-
McGraw Hill Publishing Company, 1986
Buku Teks
Graham, Linda E.
Prentice-Hall, 2000
Buku Teks
Bold, Harold Charles, 1909-
Prentice-Hall, 1976
Buku Teks
Bold, Harold Charles, 1909-
Prentice-Hall, 1985
Buku Referensi