"Real-time Rendering" by Akenine-Tomas Möller et all is one of the standard references here.

https://www.amazon.com/Real-Time-Rendering-Fourth-Tomas-Aken...

Peter Shirley's free Ray Tracing series is incredibly good as well: https://raytracing.github.io/books/RayTracingInOneWeekend.ht...

And the outstanding piece in rendering is the Physically Based Rendering book by Pharr et all (which won an Oscar): https://www.pbrt.org/

None of those are math references as such, but the thing is with graphics it's not based on first principles (well, ray tracing is kinda getting there but still has lots of artistic stuff rather than science stuff), but rather on a bag of tricks. And the math without the "bag of tricks" context may not be that clear.

Way back in the day I read either the 1st or 2nd edition of this book: https://www.amazon.com/Computer-Graphics-Principles-Practice...

It's a classic in the computer graphics field, like Knuth is for algorithms. I'd recommend it alongside the OP's new book.

EDIT: But for anyone who is reading this wanting to learn about practical computer graphics, CG:P&P is NOT the resource to use! Learning the low-level rasterization algorithms used in computer graphics is an important thing to learn at some point, just like learning assembly language provides valuable insights even if you never touch a line of assembler again. But if you actually want to write graphics code on modern hardware with GPUs, I'd highly recommend Real Time Rendering instead: https://www.amazon.com/Real-Time-Rendering-Fourth-Tomas-Aken...

https://www.amazon.com/Real-Time-Rendering-Fourth-Tomas-Aken...

try this if you have time