Below I've listed some
books I have found useful (mouse over for info or click the link to go
directly to Amazon.com)
General
Photography Books
Capturing
the Light: An Inspirational and Instructional Guide to Landscape
Photography
Another excellent book. This isn't a book that covers the basics
of photography, but provides material that will help you improve how
you see light and its effect of the landscape. Each photograph
has a description of what the author was seeing and thinking when
making the photo along with technical notes. Each photo also has
information showing what filters were used and where they were placed
(for split neutral density gradient filters).