Peterson Field Guides is a 22-book series with 49 released primary works first released in 1951 with contributions by Roger Tory Peterson, Alexander B. Klots, Frederick H. Pough, Margaret Elizabeth Murie, Roger Conant, Joseph T. Collins, Jay M. Pasachoff, Robert C. Stebbins, John J. Craighead, Joan C. Craighead and 22 others.