If you want some in depth reading about graphic design then going back the Bauhaus might be a good start. The modernist movement was a huge helping hand in the development of the discipline. Current proponents of the 'Swiss' style include Joseph Muller Brockmann and Wim Crowell - both inspirational writers.
Brockmanns Grid systems in graphic design is a bit heavy going but drills down into the mysterious fundamentals of 'the grid'.
The Film Helevtica [helveticafilm.com] is a great look at how type has shaped our surroundings and touches on much more than just the typeface itself. One of my design heroes; Eric Spiekermann, whose commentary in the film is hilarious, is another name to look out for. His book Stop Stealing Sheep and Find Out How Type Works is great little manual for typographers and designers.
For more about typography; Thinking with Type: A Critical Guide for Designers, Writers, Editors, and Students is also good one, not too dry.
A smile in the mind is an excellent look at how good design is usually delivered with wit and intellect - some lovely examples of really good graphic design.
And one last mention, How to Be a Graphic Designer: Without Losing Your Soul by Adrian Shaughnessy - more about the pracitcal side of the industry - a bit of a bible, especially for those just starting out in GD education, those on the graduate trail or those founding a studio.