There are so many great books to read on the subject of birth, but here are just a few to get you started.
Babies are Not Pizzas - They're Born, Not Delivered by Rebecca Dekker
The Doula's Guide to Empowering Your Birth: A Complete Labor and Childbirth Companion for Parents to Be by Lindsey Bliss
Birth Partner 5th Edition: A Complete Guide to Childbirth for Dads, Partners, Doulas, and All Other Labor Companions by Penny Simkin
Ancient Map for Modern Birth by Pam England
Birth Without Fear: The Judgment-Free Guide to Taking Charge of Your Pregnancy, Birth, and Postpartum by January Harshe
Ina May's Guide to Childbirth "Updated With New Material" by Ina May Gaskin