| Number | Name | Date | Kind |
|---|---|---|---|
| 3065970 | Besley | Nov 1962 | |
| 3672681 | Wolf | Jun 1972 |
| Number | Date | Country |
|---|---|---|
| 1154 | Apr 1906 | GBX |
| Entry |
|---|
| "Polyominoes" by Solomon W. Golomb; publ. by Charles Scribner's Sons.; New York, copyright 1965; pp. 116-118, 126. |
| Scientific American; Sep. 1972; pp. 176, 177, 178, 180, 182. |