The Hitchhiker's Guide to the Galaxy

1. 

   Book 1

   The Hitchhiker's Guide to the Galaxy

   Douglas Adams

2. 

   Book 2

   The Restaurant at the End of the Universe

   Douglas Adams

3. 

   Book 3

   Life, the Universe and Everything

   Douglas Adams

4. 

   Book 4

   So long, and thanks for all the fish

   Douglas Adams

5. 

   Book 5

   Mostly Harmless

   Douglas Adams

6. 

   Book 6

   And Another Thing…

   Eoin Colfer

Book data and covers from Open Library (openlibrary.org).