- http://www.mgacontrols.com/category/solenoid-valves/ illustrations of 2-way, 3-way, and pilot operated solenoid valves
- http://www.hnsa.org/doc/fleetsub/refrig/chap7.htm pp. 39–40. Solenoid valve illustration; breakaway pin / kick-off.
- http://www.smc.eu/portal/WebContent/local/UK/Pneu_Book/Solenoid_Valves.jsp Skinner valve, 1930s; magnetic path issues; wear; power; number of cycles
- http://www.surmaq.com/html/cata/parker/contr/skinner.pdf pp. 128-131; tech details of design; different terminology; welded sleeve; valve sizing. Page 128: "Skinner Valve plunger assemblies, when appropriate, use floating top and bottom seals to enhance valve performance. Floating seals permit the plunger to generate a larger actuation force to open against the pressure differential in the valve. This enables the valve to operate at higher pressure ratings." Material has implications for shading ring: copper is satisfactory for many materials, but it is unsatisfactory for coffee and urea; silver is satisfactory for those fluids. (pp 130–131.)
- http://cr4.globalspec.com/thread/56783/Shading-Ring discussion about shading coil
- Design of Shading Coils for Minimizing the Contact Bouncing of AC Contactors, doi:10.1109/HOLM.2008.ECP.34
- https://www.asconumatics.eu/images/site/upload/_en/pdf1/00022gb.pdf More detailing information about solenoid and shading coil
- http://relays.te.com/schrack/pdf/C0_v4bg_5.pdf About relay design but includes relevant information