Konig, Hartmut
Protocol engineering
Springer-Verlag, 2012
 eBooks
Meehan, Diane
An introduction to fourth generation languages
Stanley Thornes , 1990
 Buku Teks SO
Irving, John
Tangan keempat= The fourth hand
Gramedia Pustaka Utama, 2006
 Buku Teks SO
Press, Frank
Earth : fourth edition
W.H. Freeman and Company, 1986
 Buku Referensi
Schwab, Klaus, 1938-
The fourth industrial revolution
Currency, 2017
 Buku Teks