Philippines : De La Salle University Manila, 2008,
Majalah, Jurnal, Buletin
Keat, Paul G., author
Pearson Education (Prentice Hall), 2009
Buku Teks
Sydney : Sydney University Press
Majalah, Jurnal, Buletin
Boeke, Hendrik Enno., author
Leiden Universitaire Pers 1948
Buku Teks
Mann, Prem S
New York John Wiley & Sons 1995,
Buku Teks