1. Swainson, W. K. Method, medium and apparatus for producing three-dimensional figure product. US patent 4,041,476 (1977).
2. Kodama, H. Automatic method for fabricating a three-dimensional plastic model with photo-hardening polymer. Rev. Sci. Instrum. 52, 1770–1773 (1981).
3. Hull, C. W. Apparatus for production of three-dimensional objects by stereolithography. US patent 4,575,330 (1986).
4. Sachs, E. M., Haggerty, J. S., Cima, M. J. & Williams, P. A. Three-dimensional printing techniques. US patent 5,205,055 (1993).
5. Beaman, J. J. & Deckard, C. R. Selective laser sintering with assisted powder handling. US patent 4,938,816 (1990).