www.optics.heraeus-quarzglas.com - Heraeus fused silica info
www.us.schott.com - Schott flat glass products info (borofloat, robax, etc.)
www.us.schott.com - Schott tubing info
www.alumaxbath.com - Detailed information on tempered vs. annealed glass
www.glasswebsite.com - Great resource for glass history and technical info
www.c-optical.com - Recommended company for optical coating services and information. Please mention Rayotek if you contact them.