Peterson Field Guides is a 21-book series with 21 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, Margaret McKenny, Jay M. Pasachoff, Robert C. Stebbins, John J. Craighead, Joan C. Craighead, Ray J. Davis, Frank C. Craighead Jr., Donald J. Borror, Richard E. White, Lee Allen Peterson, Vincent J. Schaefer, John A. Day, Charles V. Covell Jr., Kent H. McKnight, Vera B. McKnight, John C. Kricher, Kenn Kaufman, Steven Foster, James A. Duke, Richard K. Walton, Robert W. Lawson, George A. Petrides, Olivia Petrides, Roger A. Caras, Jon L. Dunn, and Kimball L. Garrett.