Books about raytracing.

So, I've got two new books:

1. 3d computer graphics. a mathematical introduction with opengl.
2. realistic image synthesis using photon mapping.

thanks to http://www.pdfchm.com/

Anyway, the information I searched for is available in these books: general ray tracing. And the second book looks interesting: I was always interested in global illumination methods at all and particular in photon mapping.