Here are five books that have been truly valuable to me in professional life. I can name more but these five are worth highlighting.

Growing a Business
Paul Hawken
Fireside
First published in the early eighties, this book served as a spiritual guide for me for how run a business. It’s not a how-to book and it’s not about money. It is about thinking of your business as something you live to do.

http://www.amazon.com/Growing-Business-Paul-Hawken/dp/0671671642

On Writing Well
William Zinsser
Harper Resource
You can open this book to any page and you will find something useful. It is as much a guide to creative thinking and communication as it is about tips on writing clearly. I’ve turned to this repeatedly.

http://www.amazon.com/Writing-Well-25th-Anniversary-Nonfiction/dp/0060006641

Typographie
Emil Ruder
A. Niggli
A first glance this is a Swiss bible of typography. Wonderful yet dated. For me, however, it remains a model of the expressive possibilities of type regardless of the current trend. This book opened up the gate for me.

http://www.amazon.com/Typographie-Manual-Design-Emil-Ruder/dp/3721200438

A Designers Art
Paul Rand
Yale
Rand’s insightful, eclectic reflections on graphic design are timeless and reflect a deep intellect and remarkable visual acuity.

http://www.amazon.com/Paul-Rand-Designer%60s-Art-Mr/dp/0300082827

The Visual Display of Quantitative Information
Edward Tufte
Graphics Press
Tufte’s lucid and playful treatise on presenting data is enlightening for designers and lay people alike. A real treat. Beautifully produced.

http://www.edwardtufte.com/tufte/books_vdqi

Rick Landesberg, Landesberg Design
www.landesbergdesign.com