Ray Tracing in a Weekend Series. Most the way through the first book and I plan on continuing it. [1][2][3]
Tiny Renderer - How OpenGL Works. A software renderer in 500 lines of code. Wiki has a full tutorial. [4]
The Book of Shaders. A step by step introduction into fragment shaders. [5]
[1] https://www.amazon.com/_/dp/B01B5AODD8
[2] https://www.amazon.com/_/dp/B01CO7PQ8C
[3] https://www.amazon.com/_/dp/B01DN58P8C
[4] https://github.com/ssloy/tinyrenderer/wiki
[5] https://thebookofshaders.com/