Nvidia: GPU-Based Importance Sampling

Coding Labs: Physically based rendering

Wolfire Games - Physically based rendering

Background: Physics and Math of Shading by Naty Hoffmann

Real shading in Unreal Engine 4

Physically Based Shading and Image Based Lighting

Implementation Notes: Runtime Environment Map Filtering for Image Based Lighting

Physically Based Shading at Disney

Microfacet Models for Refraction through Rough Surfaces

Moving Frostbite to PBR