I agree with what Clinton Freeman suggested. I haven't read Hourences' book, but I have gone through some of his video tutorials and his website is highly informative so I would bet his book is excellent.
The Art of Game Design:A Book of Lenses is a great book and takes you through the game design process but doesn't delve too much into level design specifically as I recall. It covers how to get started designing a game all the way through pitching your ideas to a publisher.
Scott Roger's book Level Up is another fantastic book in my opinion. This book has a a section specific to level design. That section includes things like hand drawn level maps that were used to concept actual levels, what makes a level fun/boring, how to draw the attention of the player, and the different types of level layouts. There are a lot of other interesting topics in the book as well and it was entertaining to read.
Hope that helps. Good luck!