Gregory, Kenneth J., author
Sage , 2010
Buku Teks
Easterbrook, Don J.
Prentice-Hall, 1999
Buku Teks
Easterbrook, Don J.
Macmillan Publishing Company, 1993
Buku Teks
Masselink, Gerhard, author
Hodder Education, 2011
Buku Teks
Leopold, Luna B., author
Dover, 1995
Buku Teks