Resources for Learning OS Dev

Recently I've been learning os dev and there's a surprising amount of freely available resources for getting started with little to no direct experience (with OS dev, you need to know how to program already). Below is a list of the resources I've found inredibly helpful.

• OS dev wiki
• Writing an OS in Rust (and the first edition)
• Redox OS
• Serenity OS
• Operating Systems: Three Easy Pieces