Perlin, Ken. "Making Noise". noisemachine.com. Ken Perlin. Archived from the original on October 8, 2007.
"Ken's Academy Award". Archived from the original on 2018-05-01. Retrieved 2011-05-29.{{cite web}}: CS1 maint: bot: original URL status unknown (link) of Ken Perlin's 'coherent noise function'