Stein, Lincoln D.
Official guide to programming with CGI.pm
Wiley, 1998
 Buku Teks
Guide to official statistics
Central Statistical Office
Her Majesty`s Stationery Office, 1986
 Buku Referensi
Oehler, Karsten
IBM Cognos TM1 : the official guide
McGraw-Hill, 2012
 Buku Teks
Hayes, Denis
The Official earth day guide to planet repair
Island Press, 2000
 Buku Teks
Anderson, Chris
TED talks: the official TED guide to public speaking
Headline Publishing Group, 2016
 Buku Teks