Number | Name | Date | Kind |
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4335819 | Weisman et al. | Jun 1982 |
Number | Date | Country |
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1-199498 | Aug 1989 | JPX |
4-116891 | Apr 1992 | JPX |
Entry |
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"Implementation of Logic Book/Cage Keys", IBM Technical Disclosure Bulletin, vol. 33, No. 10B, Mar., 1991, pp. 235 241. |