COMMON NYMPHS OF EASTERN NORTH AMERICA
In my opinion this is an excellent book, it was written with a view of matching the hatch while fishing nymphs and it was written by Professors who are fly fishers.
Even though the content is based on eastern insects there is much that any angler can learn from this volume. The information is tight, compact and understandable and the photograph is pretty good. As its title says Common Nymphs the authors have covered all of the common aquatic organisms with the angler will generally be imitating on the rivers of Eastern North America.