You should definitely read The Goal once you've completed The Phoenix Project. There's a great audiobook version of it on Audible that is set up like a radio play :)
My other go-to DevOps books:
and a non-technical book, but super essential for anyone working through changes in an organization, team, or personal: Switch: How to Change Things When Change Is Hard.
Accelerate, Switch, the Goal +++
DevOps is a broad topic. From my personal book shelf I would recommend (in addition to Matt Stratton's suggestions!)
Also the following additional resources are good for creating highly maintainable and reliable applications:
We wrote an entire article on the same. Here are our picks
Some more insights in this article blog.shippable.com/devops-resource...
We’re a place where coders share, stay up-to-date and grow their careers.
We strive for transparency and don't collect excess data.