Graber, Mark A., author
Oxford University Press, 2015
Buku Teks
Fisher, Louis, author
McGraw-Hill, 1988
Buku Teks
Hird, John A., author
Wadsworth , 2004
Buku Teks
Paneth, Donald, author
Facts on File, 1983
Buku Referensi
Herget, James E.
Texas: Rice University Press, 1990,
Buku Referensi