Books

For further information on ray tracing in graphics, see the following books.

An Introduction to Ray Tracing (Edited by A. Glassner, Academic Press, 1989).: The classic and still relevant book.
Ray Tracing from the Ground Up (K. Suffern, AK Peters, 2007).: A very detailed beginner book.
Fundamentals of Computer Graphics (P. Shirley and S. Marschner, AK Peters, 2009).: A concise description of ray tracing.
Advanced Global Illumination (P.Dutré, P. Bekaert and K. Bala, AK Peters, 2006).: A general discussion of realistic batch rendering algorithms.
Physically Based Rendering (M. Pharr and G. Humphreys, Morgan Kaufmann, 3rd edition, 2016).: A great deal of detailed information on ray tracing and algorithms that use ray tracing.
Realistic Image Synthesis Using Photon Mapping (H. Jensen, AK Peters, 2001).: A detailed description of photon mapping.
Real-Time Rendering (T. Akenine-Müller, E. Haines and N. Hoffman, AK Peters, 2008).: A discussion of using ray tracing interactively for picking and collision detection, as well as a detailed discussion of shading and ray-primitive intersection.