D,G,F

전체 목록:

http://graphicrants.blogspot.kr/2013/08/specular-brdf-reference.html

https://learnopengl.com/PBR/Theory

실제 게임에서의 변화 (No visibility function vs Schlick-Smith Visibility function)

Lazarov-Physically-Based-Lighting-in-Black-Ops (Siggraph 2011 Advances in Real-Time Rendering Course)