Bliley Electric Company History: The Early Years, 1930-1955
History of the company that invented and patented the overtone crystal, etch-to-frequency and variable crystals. Source for ads, engineering bulletins, patents and manuals. http://www.Bliley.net/XTAL/
Crystal Grinding
FT243 information compiled by Paul Carreiro, N6EV. http://www.qsl.net/n6ev/ft243.txt
Crystal Info
A handy historical chart of old crystal holders with dimensions, and suppliers. http://pages.cthome.net/fwc/XTAL.HTM
Crystal multiplier chart
WB6SZS, Eugene Rippen's comprehensive chart for crystal use on the HF, VHF and UHF bands. http://www.muchstuff.com/xtal-frq.htm
Technical Information
A useful technical reference page for Crystals. http://www.icmfg.com/technicaldata.html
Crystal Oscillators
From N6EV. Tube oscillator schematics, and discussion. http://www.qsl.net/n6ev/68-xtal.html