Town planning into the 21st century / edited by Andrew Blowers and Bob Evans
Routledge, 1997
 Buku Teks
Makridakis, Spyros G., author
Forecasting, planning, and strategy for the 21st century
The Free Press, 1990
 Buku Teks
Gesker, Ronald D., author
Media planning and buying in the 21st century
2020:Marketing Communications LLC, 2015
 Buku Teks
Ward, Ralph D.
21st century corporate board
John Wiley and Sons, 1997
 Buku Teks
Yablonsky, Lewis, author
Juvenile delinquency into the 21st century
Wadsworth, 2000
 Buku Teks