Bryson, Bill
I'm a stranger here myself : notes on returning to America after twenty years away
Broadway Books, 2000
 Buku Teks SO
Drucker, Peter Ferdinand, 1909-2005
America's next twenty years
Harper & Brothers, 1957
 Buku Teks SO
Davidson, Jamie S.
Indonesia: twenty years of democracy
Cambridge University Press, 2018
 Buku Teks SO
Celebrating twenty years with Deloitte in Indonesia
Deloitte Touche Tohmatso limited
Deloitte Touche Tohmatso limited, 2010
 Buku Referensi
Susan, Jane
Lady Susan, the Watsons and Sanditon : discussion notes for book groups/ by Jane Austen.
CAE Book Groups, , 2008
 Buku Teks SO