Navigation Book to Read

Recently, one of my students showed me a book by Greg Davenport. This was a new one for me.   Davenport's book Advanced Outdoor Navigation is a great read.

This book is very detailed and is an excellent resource for the backcountry navigator.  I found a copy on Amazon.  My copy was printed in 2006.  The GPS section needs to be brought up to date.  

I wish it was still in print as I'd use it as the required reading material in my next class.