Melanie
Well-known member
Project Muse has currently an offer of ebooks (PDF) for free until March 30, 2020.
There are many interesting books on birds:
https://muse.jhu.edu/search?action=...subscription:y&limit=format:book&min=1&max=50
There are many interesting books on birds:
https://muse.jhu.edu/search?action=...subscription:y&limit=format:book&min=1&max=50