1. John M. Photo-glyph recording. US Patent 2,775,758, December 1956.
2. Hull C. Apparatus for production of three-dimensional objects by stereolithography. US Patent 4,575,330, March 1986.
3. Deckard C. Method and apparatus for producing parts by selective sintering. US Patent 4,863,538, September 1989.
4. Crump S. Apparatus and method for creating three-dimensional objects. US Patent 5,121,329, June 1992.
5. Sachs E, Haggerty J, Cima M, Williams P. Three-dimensional printing techniques. US Patent 5,204,055, April 1993.