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