Kajiya, James T. (1985) Anisotropic reflection models; ISBN 0-89791-166-0; SIGGRAPH '85 Proceedings of the 12th annual conference on Computer graphics and interactive techniques; ACM SIGGRAPH Computer Graphics; Vol. 19; No. 3; 15-21; 10.1145/325165.325167
Kajiya, James T. and Von Herzen, Brian P. (1984) Ray tracing volume densities; ISBN 0-89791-138-5; SIGGRAPH '84 Proceedings of the 11th annual conference on Computer graphics and interactive techniques; ACM SIGGRAPH Computer Graphics; Vol. 18; No. 3; 165-174; 10.1145/10.1145/964965.808594