Five of the best books, in no particular order, are what I would regard as the best Graphic Design books and you must have on your bookshelves.

The Visual History of Type
Author: Paul McNeil
Price: £39

How To
Author: Michael Bierut
Price: £22.75

Draplin Design Co: Pretty Much Everything
Author: Aaron Draplin
Price: £18.21

The Design Process
Author: Karl Aspelund
Price: £64.80

Graphic Design: The New Basics
Author: Dawn Sokol
Price: £21.99