NOTES

1. (from http://www.flipcode.com/archives/Raytracing_Topics_Techniques-Part_5_Soft_Shadows.shtml)

Keep this in mind: 
    FindNearest( Ray( a_IP + a_Dir * EPSILON, a_Dir, ++m_CurID ), tdist, prim );

This is from code checking for occlusion of a light source. Notice how he sets
the origin of the ray to EPSILON away from the original hit point. This is
presumably so the scattered ray doesn't hit the original object again. I don't
seem to have this problem, but this is something that I should keep in mind
should I start encountering weird bugs.

2. Indirect illumination tips (http://www.lamrug.org/resources/indirectips.html, try Google cache)
3. Energy conservation in games ( http://www.rorydriscoll.com/2009/01/25/energy-conservation-in-games/)
4. https://seblagarde.wordpress.com/2012/01/08/pi-or-not-to-pi-in-game-lighting-equation/