| Number | Date | Country | Kind |
|---|---|---|---|
| 3103583 | Feb 1981 | DEX |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3081089 | Gustafson | Mar 1963 | |
| 3655201 | Nichols | Apr 1972 |
| Number | Date | Country |
|---|---|---|
| 170062 | Dec 1977 | HUX |
| 55-3956 | Jan 1980 | JPX |
| Entry |
|---|
| "Notes on Rubik's Magic Cube" by David Singmaster, Published by Enslow Publishers, Hillside, NJ, copyright 1979, p. 29. |