The Blinn-Phong Normalization Zoo
http://www.thetenthplanet.de/archives/255
http://www.farbrausch.de/~fg/stuff/phong.pdf
https://seblagarde.wordpress.com/2011/08/17/hello-world/
http://www.thetenthplanet.de/archives/255 Schüler, “The Blinn-Phong Normalization Zoo”