As well as offering over 15,500 standard round wire compression, die, extension, torsion, disc springs, constant-force and wave springs, Lee Spring also has some very useful technical literature available.
The Engineers guide to designing and specifying compression, extension and torsion springs is an excellent book, with over 20 A4 pages of formulae, tables, standards, conversions and other essential information. This is available as a hard copy on request or it can be downloaded free of charge from the company's website.
Other PDF downloads are:
All of these are available at www.leespring.co.uk/pages/downloads.html.