Referenced by|
| US4147343 | 2 Jun 1978 | 3 Apr 1979 | | Acrobatic amusement device | | US4244567 | 10 Dec 1979 | 13 Jan 1981 | George H. Linzee | Space tumbler | | US4298197 | 29 Jan 1979 | 3 Nov 1981 | | Balance assist for rotating recreational devices | | US4304400 | 28 Mar 1980 | 8 Dec 1981 | | Manually powered amusement device |
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