| Number | Name | Date | Kind |
|---|---|---|---|
| 3272496 | Halopoff et al. | Sep 1966 | |
| 3718325 | Nystrom | Feb 1973 | |
| 3958367 | Fairman | May 1976 | |
| 4076433 | Halopoff | Feb 1978 | |
| 4472910 | Iha | Sep 1984 | |
| 4640049 | Duncan | Feb 1987 | |
| 4731905 | Milano et al. | Mar 1988 | |
| 4757853 | Price | Jul 1988 | |
| 4824276 | Ginell | Apr 1989 | |
| 4852378 | Greco | Aug 1989 | |
| 5004216 | Boudreau | Apr 1991 |
| Entry |
|---|
| Henry Martin "Adjustable Extension Springs" in Douglas C. Greenwood, Ed. Product Engineering Design Manual (McGraw Hill Book Company, Inc. New York, 1959) pp. 320-321. |
| Federico Strasser "29 Ways to Fasten Springs" New Ideas and Data for Product Design Improvements in Product Engineering (McGraw--Hill Publication, New York, 1960) pp. 10-13. |