https://www.amazon.com/OpenGL-Shading-Language-Cookbook-high...

https://www.amazon.de/Graphics-Shaders-Practice-Michael-Bail...

https://www.amazon.de/Real-Time-Rendering-Fourth-Tomas-Akeni...

https://www.amazon.de/Physically-Based-Rendering-Theory-Impl...

Or grab some online content instead,

http://www.pbr-book.org/

https://developer.nvidia.com/gpugems/GPUGems/gpugems_pref01....

https://developer.nvidia.com/gpugems/GPUGems2/gpugems2_insid...

https://developer.nvidia.com/gpugems/GPUGems3/gpugems3_pref0...

https://developer.download.nvidia.com/CgTutorial/cg_tutorial...

Naturally most of the stuff I linked to, doesn't use necessarily GLSL ES, however it is relatively easy to translate the concepts and ideas into it, given how most shading languages happen to be either a C or C++ based dialect.

[1a, 1b, 1c] Computer Graphics, Principles and Practice Series [2] Physically Based Rendering [3] Real Time Rendering

---

[1a] https://www.amazon.com/Computer-Graphics-Principles-James-Fo... [1b] https://www.amazon.com/Computer-Graphics-Principles-Practice... [1c] https://www.amazon.com/Computer-Graphics-Principles-Practice... [2] https://www.amazon.com/Physically-Based-Rendering-Theory-Imp... [3] https://www.amazon.com/Real-Time-Rendering-Third-Tomas-Akeni...