Hi, All--
In this time of home confinement and the luxury of birdwatching-at-will that it allows, I want to build my birding library. What Go-To and/or Must Have volumes should I aquire? In addition to the Peterson, Sibley (East & West), and National Geographic field guides for North America, I already have: Karlson & Dunne, Gulls Simplified; Dunne et al, Hawks in Flight; Wheeler & Clark, A Photographic Guide to North American Raptors; and O'Brien, The Shorebird Guide
Thanks!