Presley, John W., author
Prentice-Hall, 1982
Buku Teks
Barrass, Robert, author
Routledge, 1995
Buku Teks
Clouse, Barbara Fine, author
McGraw-Hill, 2005
Buku Teks
Niles Christensen [and others]
Illinois Scott, Foresman , 1984
Buku Teks
Peters, Pam, author
Cambridge University Press, 2006
Buku Referensi