Two must reads that should be first on your list.
Ray Tracing in One Weekend
Ray Tracing: The Next Week

An online book that was once in print but was put up online only because the authors didn't like the quality of the printers work.
Online book Physically Based Rendering

Pretty much a complete list of must read books
List of books on Eric Haine's Real Time Rendering site

Pixar in a box: Kahn Academy
[Rendering]{https://www.khanacademy.org/partner-content/pixar/rendering)
Their complete list

vkQuake
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