Number | Name | Date | Kind |
---|---|---|---|
1518889 | Wooster | Dec 1924 |
Number | Date | Country |
---|---|---|
170062 | Dec 1977 | HUX |
55-3956 | Jan 1980 | JPX |
Entry |
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"Metamagical Themas", by Douglas R. Hofstadter, Scientific American, Mar. 1981, pp. 20-22, 25-28,30,32,35,39. |
"Notes on Rubik's Magic Cube", by David Singmaster, published by Enslow Publishers, Hillside, N.J., copyright 1981, p. 38, lines 17-23, relied on. |