Start with high-confidence zoology books, then narrow by subgenre or adjacent topics.
The Natural History of Unicorns
Dr. Chris Lavers
Wildlife on the Planet Furaha
Gert van Dijk
Animal
DK, D.K. Publishing
The Encyclopedia of Animals
David Alderton
Wildlife of the World
DK, Don E. Wilson
Zoology
DK, Smithsonian Institution
Immune System of Animals
Shyamasree Ghosh
