Elliott Coues

They treat of many of the species found in Pennsylvania.

Books on general aspects of ornithology which you will find useful are Wetmore's The Migrations of Birds, Ball's Bird Biographies, Blanchan's Bird Neighbors, and Birds That Hunt and Are Hunted, Chapman's What Bird is That?, Coues' Key to North American Birds, the National Geographic Society's Book of Birds, and Forbush's Useful Birds and Their Protection.

Magazines.

The Proceedings of the Delaware Valley Ornithological Society, published under the title Cassinia, contain a wealth of material interesting to the Pennsylvania student.