Patrick M. Hanrahan (July 26, 1982). “Creating volume models from edge-vertex graphs”. Proceedings of the 9th annual conference on Computer graphics and interactive techniques - SIGGRAPH '82. ACM. 77–84. doi:10.1145/800064.801265. ISBN978-0897910767
Pat Hanrahan; Jim Lawson (August 4, 1990). “A language for shading and lighting calculations”. SIGGRAPH 1990: Proceedings of the 17th Annual Conference on Computer Graphics and Interactive Techniques24 (4): 289–298. doi:10.1145/97880.97911.