Actually, in my original question I was looking for landscape design books meaning plant materials. Design of beds (for foundation plantings, beds on property, etc.). But, if you know any good books on hardscaping e.g. retaining walls, that would be great too. Thanks! Any info would be greatly appreciated.
A good plant book would be Dirr's Guide to woody and ornamental. Basically it tells you everything you need to now about most plants. A bit technical, but very informative.
As for design books, there really are a endless supply. Though you say you don't want a 'homeowner' book, most all give the same basic design principles. Homeowner books, as you would call them, actually do give you a lot of ideas. The fact is, there are basic design principle that are so simple, yet so often forgotten, that are usually mentioned in every desing bood out there. Even the "landscaping for dummies" book would be of help if you are unaware of any of the basics.
Thats what so great about this field. There's a million different ways to look at things. A good start would be to go to one of big book stores and spend some time looking at what they have. I must have 50 books at least, from just picture manuals to books with library's of landscape drawing symbols. I'm always sitting down and looking through them.
Ideas can be found anywhere, and usually are in the weirdest places. I used a book about castles of England once that had a beutiful formal garden around it as the basis for one of my designs.
Some books are very basic, and may not be of some help, but all in all, they all have something to offer.
I have a great design book for retaining walls, grading, stormwater management and etc. The title is "Landscape Architecture Construction" by Landphair and Klatt. Its great book for someone involved in complex site planning who needs mathmatical solutions to determine wall stresses, runoff calculations and ect. The only complaint have against this book is that occasionally they skip a step and its take awhile to figure how they got from one step to the next. I have a mechanical engineering degree and can usually figure it out what they did but someone with a more limit math background could possibly get lost. All in all though it the best engineering type landscape book I have seen.
Take a look at your local Barns and Noble. I have about 15 books and they are great. They save me a lot of $$$$, you don't have to worry about have your clients come back and tell you thats not what I was looking for... They are cheap too, around 15-25 bucks