For a high-level overview, see these websites:
MinimumCD.org (signatories: Dave Farley, Bryan Finster, others)
continuousdelivery.com (Jez Humble)
For a deeper overview, see these books:
Continuous Delivery: Reliable Software Releases through Build, Test, and Deployment Automation (Jez Humble, Dave Farley)
Continuous Delivery Pipelines: How To Build Better Software Faster (Dave Farley)
Accelerate: The Science of Lean Software and DevOps: Building and Scaling High Performing Technology Organizations (Nicole Forsgren PhD, Jez Humble, Gene Kim)
For further learning:
Continuous Delivery (YouTube Channel) (Dave Farley)