Number | Date | Country | Kind |
---|---|---|---|
3010686 | Mar 1980 | DEX |
Number | Name | Date | Kind |
---|---|---|---|
2018860 | Lord | Oct 1935 | |
2132840 | Workman et al. | Oct 1938 |
Number | Date | Country |
---|---|---|
2396895 | Mar 1979 | FRX |
Entry |
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H. K. Baumeister, C. C. Kilmer; IBM Technical Disclosure Bulletin; vol. 22, No. 6, Nov. 1979, pp. 2389-2390. |