Energy, environment and sustainable development: Challenges for the 21st century
1993
 Buku Teks
Vesterman, William, author
Readings for the 21st century / William Vesterman and Josh Ozersky
[publisher not identified], [date of publication not identified]
 Buku Teks
Strategic marketing cases for 21st century Asia
by John A. Quelch ... [and others]
Prentice-Hall, 2000
 Buku Teks
Garcia, Ofelia, author
Bilingual education in the 21st century : a global perspective
Wiley-Blackwell , 2009
 Buku Teks
Bagley, Constance E., author
Managers and the legal environment : strategies for the 21st century
South Western Cengage Learning, 2013
 Buku Teks