These few are very good:

http://www.amazon.com/Medieval-Maps-...12918&sr=1-151
http://www.amazon.com/How-Draw-Maps-...12918&sr=1-152
http://www.amazon.com/Maps-Imaginati...1513125&sr=1-6
http://www.amazon.com/Flattening-Ear...513125&sr=1-19


I have these books, and they are all good resources.

Sandeman