UTZ, Peter, author
Prentice-Hall, 1982
Buku Teks
Smith, Walter Denton
West Publishing, 1939
Buku Teks
Donner, A. M.
W.E.J Tjeenk Willink, 1977
Buku Teks
Armstrong, Michael, author
Gramedia, 2003
Buku Teks
Espich, James E.,
Fearon Publishers, 1967
Buku Teks