Number | Name | Date | Kind |
---|---|---|---|
1999861 | Bowden | Apr 1935 | |
3410037 | Empson et al. | Nov 1968 | |
3951562 | Fyfe | Apr 1976 | |
4781003 | Rizza | Nov 1988 |
Number | Date | Country |
---|---|---|
232203 | Aug 1987 | EPX |
Entry |
---|
MM Systems Corporation, Systems for Seismic and Expansion Control, 1988, p. 4. |