Have a look at a book by Tomas Akenine-Möller & Eric Haines which is a must-have thing for anyone interested in real-time rendering.
Ray Tracing Gems will provide you with key building blocks for developers of games, architectural applications, visualizations, and more. It features experts in rendering discussing their knowledge by explaining everything from nitty-gritty techniques that will improve any ray tracer to mastery of the new capabilities of current and future hardware.
The book was written by Eric Haines and Tomas Akenine-Möller, a Distinguished Research Scientist at NVIDIA, Sweden, since 2016, and now a professor in computer graphics at Lund University. You can learn more and get the book here.