|
| US3990053 | 15 Oct 1973 | 2 Nov 1976 | International Business Machines Corporation | Stored program selector for electronic calculator |
| US4258251 | 10 Abr 1979 | 24 Mar 1981 | University of Strathclyde | Apparatus for use in ordering trials |
| US4409657 | 4 May 1981 | 11 Oct 1983 | | Time clock for recording the identification of a person |
| US4847791 | 16 Ago 1982 | 11 Jul 1989 | | Timekeeping system |
