Here are a few reference books and media that we recommend:

Pennsylvania Natural History DVDs by Tom Diez.
The Amphibians of Pennsylvania by Tom Diez.
This DVD is forty five minutes long and features the 23 species of salamanders and 17 species of frogs and toads that are listed for the state. Included with the DVD is an informative booklet containing species accounts, and a glossary.
Order Form | Information Page

The Snakes of Pennsylvania by Tom Diez.
This DVD features the 21 species of snakes that have been found in Pennsylvania. This educational and entertaining program is 50 minutes long. The amphibian booklet contains information on the biology and life history of each species, and a helpful glossary.
Order Form | Information Page

Other Publications:

• “The Biology of Plethodontid Salamanders” by Richard C. Bruce
• “The New Encyclopedia of Snakes” by Chris Mattison
• “Rattlesnake, Portrait of a Predator” by Manny Rubio
• “Snakes and Snake Hunting” by Carl Kauffeld
• “Rattler!” by Chris Mattison
• “Rattler Tales From Northcentral Pennsylvania” by C.E. Brennan.