Montgomery Bird Club: https://www.montgomerybirdclub.org

Maryland Ornithological Society: https://mdbirds.org/

American Birding Association (ABA): https://www.aba.org/

American Ornithological Society: https://americanornithology.org/

Nature Forward (formerly Audubon Naturalist Society): https://natureforward.org/

National Audubon Society: https://www.audubon.org/

Cornell Laboratory of Ornithology: https://www.allaboutbirds.org/news/

eBird: https://ebird.org/home

Handbook of Birds of the World (Subscription): https://birdsoftheworld.org/bow/home

Maryland & D.C Bird Discussions: http://www.mdbirding.com/ebird.html

Latest Montgomery County Sightings: https://ebird.org/region/US-MD-031

The Stokes Field Guide to the Birds of North America (2010) by Donald Stokes and Lillian Stokes

Peterson Field Guide to Birds of North America (2008) by Roger Tory Peterson and Lee Allen Peterson

National Wildlife Federation Field Guide to Birds of North America (May 3, 2007) by Edward S. Brinkley

The Sibley Field Guide to Birds of Eastern North America (2016) by David Sibley

The Crossley ID Guide: Eastern Birds (2011) by Richard Crossley

National Geographic Field Guide to the Birds of North America (2017) by Jon L. Dunn and Jonathan Alderfer

Owl Moon Raptor Center

Second Chance Wildlife Center 

Montgomery County Animal Services and Adoption Center 

Ornithology: Foundation, Analysis, and Application by Michael L. Morrison et al. (2018), ISBN: 978-1421424712

Ornithology, 4th edition by Frank B. Gill, Richard O. Prum, and Scott K. Robinson (2019), ISBN: 978-1464184369

Handbook of Bird Biology (Cornell Lab of Ornithology), 3rd edition by Irby J. Lovette and John W. Fitzpatrick (editors), (2016), ISBN: 978-1118291054