The Pocket-sized Reference Book Series Each book covers a subject from science, nature, history and art. Each book is researched, written and checked by experts. Each is systematically organized for easy access to information. The visual approach brings the subjects to life for all readers, and makes them easy to understand. Each book contains tables, figures, glossary and index. If you have ever wanted to find information on a subject, but not wanted to got to specialized tomes, you will want Firefly Pocket Guides. They are easy to handle and organized for easy reference.