Listening and human communication in the 21st century / edited by Andrew D. Wolvin
Wiley-Blackwell, 2010
 eBooks
The muslim world in the 21st century: space, power, and human development
edited by Samiul Hasan
Springer, 2012
 eBooks
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