"The Essential Wilderness Navigator: How to Find Your Way In the Great Outdoors, Second Edition" is a good starter book, which I own as well.
It is a good primer, one of the better ones.
After that there are about a million left to read...

One thing I noted with this book as well as half a dozen others is
They ignore the Grid-magnetic angle and focus on true-magnetic as though grid was only for surveyors. I wonder how many other forum members have noticed this ?
In view of the fact that such a large number of maps use UTM (with a printed overlay) in fact the Grid-magnetic is paramount.
In fact for most maps other than aviation or marine it's true or geographical north that's not used (unless your doing celestial navigation). Of course the US Army FM covers it extensively.