Books non fiction:
Dearest Pet: On Bestiality by Midas Dekkers
Evolution’s Rainbow by Joan Roughgarden
Uniquely Dangerous by Carreen Maloney
Dog Love by Marjorie Garber
Wet Goddess by Malcolm J. Brenner
Loving Animals: On Bestiality, Zoophilia and Post-Human Love by Joanna Bourke (Expected publication: November 5th 2020)

The Other End of the Leash: Why We Do What We Do Around Dogs by Patricia B. McConnell
ANIMALS as Sex Partners by Edwin Harris ?

Growing Up In The Orgone Box: Secrets Of A Reichian Childhood by Malcolm J. Brenner
The Horseman: Obsessions of a Zoophile by Mark Matthews
Sleeping with Dogs: A Peripheral Autobiography

book fictions:
Bear by Marian Engel

Understanding Bestiality And Zoophilia by Hani Miletski

Animal passions directed by Christopher Spencer
Donkey love Directed by Daryl Stoneage

The death of dick long directed by Daniel Scheinert

Awkward Conversations with Animals I've Fucked by Rob Hayes
The Goat, or Who is Sylvia? by Edward Albee

not necessarily zoo but still cool:
My Dog Tulip by J.R. Ackerley