Watson, Ian, author
Morgan Kaufmann, 2003
Buku Teks
Juma, Calestous, author
UN Millenium Project, 2005
Buku Teks
Tuomi, I Ikka
Metaxis, 1999
Buku Teks
Peruta, Maria Rosaria Della, author
Emerald, 2016
eBooks
John W. Williamson
Sage Publications, 2002
Buku Teks