Depends whether the books are to inspire or teach.
Most general digital photography books are pretty OK at teaching you the basics you need to know and most text books that are specifically tailoured to landscapes are pretty dull and tend to over complicate.
I would recommend picking up all the tecniques from various different sources and maybe going on a 1 day course with someone who knows what they are doing and then collect works / books of inspirational work to aspire to.
I have the first five Landscape Photographer of the Year books - once the basics are understood, it is far better in my view to look at inspirational work and look at composition, use of light and time of day / year to get the "feel".
I have personally found these two pretty inspirational, particularly as they give you an insight into how they create their work - Full Frame - David Noton - Lake District - Alastair Lee
Alot of Landscape books are very dull and badly writtten by naff photographers. Rather than be bored stupid looking at dull sunset photos, it would probably be best to get a book that covers loads of amazing photographers.
I own both of these books and they are great, especially the second one which includes loads of amazing landscape photographers like Ansel Adams, William Eggleston, and Andreas Gursky.
Landscape photography isn't particularly challenging in technical terms, the difficulty is actually getting out there and shooting it, and being in the right place at the right time (with a tripod). As mentioned, Michael Freeman's books are good as he gives an insight into composition and I've also found Lee Frost's books fairly informative in the past, they both have quite a wide range of books covering all subjects IIRC.
Lee Filters have two interesting books called Inspiring Professionals and Inspiring Professionals 2, both of which give a breakdown of how the images were put together, especially interesting are the diagrams explaining how their filters were used to enhance the sky etc. Both books can be previewed and you can clearly see the diagrams and how useful they are.
Blimey, this has given me a lot to think about guys. A lot of these are v expensive new, blimey. I was thinking more of a how-to not just a picture book but something with insight or a guide as to how they did it. Got about 20 tabs open now so will get looking
For book on photography there is one person I would say will cover just about everything in a way that makes seance, its Michael Freeman ones to look for might be to start with are 'The Photographers eye' and 'The Photographers Mind' both worth a read by anyone into photography. Don't for get to look up all his books.