Wonderful book! If you’re the collector type there is a fabulous 1981 first edition published by Houghton Mifflin ISBN: 0395286654. I believe this early hardcover edition is what got most of the press for minor errors. Here are some other recommendations for interesting titles that I feel are within the same spirit of interest:
The Worlds of J. R. R. Tolkien by John Garth ISBN: 069119694X
Flora of Middle-Earth: Plants of J.R.R. Tolkien's Legendarium by Walter Judd ISBN: 0190276312
The Science of Middle-earth: A New Understanding of Tolkien and His World by Steyer and Mangin ISBN: 1643139541