Original Dune is a term used on the Dune Wiki to refer to the various Dune novels and reference materials written by Frank Herbert.
This includes information from:
Dune
Dune Messiah
Children of Dune
God Emperor of Dune
Heretics of Dune
Chapterhouse: Dune
The Road to Dune
Dune 7
Dune World
The Prophet of Dune