Palmer, Monte, author
Thomson Wadsworth, 2007
Buku Teks
editor, Avraham Sela
Continuum, 2002
Buku Referensi
Harari, Maurice, author
Prentice-Hall, 1962
Buku Teks
Andersen, Roy R., author
Pearson/Prentice Hall, 2007
Buku Teks
Andersen, Roy R., author
Longman, 2012
Buku Teks SO