Number | Date | Country | Kind |
---|---|---|---|
011117/77 | Sep 1977 | CHX |
Number | Name | Date | Kind |
---|---|---|---|
3633167 | Hedin | Jan 1972 | |
3751718 | Hanchett | Aug 1973 | |
3766522 | Marsh | Oct 1973 | |
4050063 | Schull | Sep 1977 |
Entry |
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Platteter, Dale; "Digital Combination Lock is Virtually Crackproof", Nov. 11, 1976; Electronics, pp. 100-101. |