Smith, Roy H.
International political economy in the 21st century : contemporary issues and analyses
Routledge, 2017
 Buku Teks
Waters, Dan
21st century management: keeping ahead of the Japanese and Chinese/ Dan Waters
Prentice-Hall, 1991
 Buku Teks
Town planning into the 21st century
edited by Andrew Blowers, Bob Evans
Routledge, 1997
 Buku Teks SO
The 21st century world atlas
Trident Press, [Date of publication not identified]
 Buku Referensi
Ward, Ralph D.
21st century corporate board
John Wiley & Sons, 1997
 Buku Teks SO