http://www.plcs.net/contents.shtml

http://www.plccable.com/

http://tecnologiadelosplasticos.blogspot.com/2011/03/extrusion-de-materiales-plasticos.html

http://www.wisetool.com/steelgrade.htm

http://www.areatecnologia.com/materiales.htm

http://www.crucible.com

http://www.areatecnologia.com/Dibujo-tecnico.htm

http://www.esab.com.ar/ar/sp/education/blog/tags.cfm?tag=Process

http://www.wisetool.com/manufacturing/angle.htm