http://renderman.pixar.com/view/non-commercial

https://forums.unrealengine.com/showthread.php?446-It-would-be-really-nice-to-see-support-for-different-anti-aliasing-types

http://www.gamedev.net/page/community/iotd/index.html/_/real-time-realistic-rendering-and-lighting-of-forests-r187

http://www.eugenedeon.com/?project=importance-sampling-microfacet-based-bsdfs-using-the-distribution-of-visible-normals

http://www.johndcook.com/blog/2014/05/29/normal-approximation-details/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+TheEndeavour+%28The+Endeavour%29