| Number | Name | Date | Kind |
|---|---|---|---|
| D. 270072 | Tobias | Aug 1983 | |
| 1189598 | McLean | Jul 1916 | |
| 2548043 | Muhlhauser | Apr 1951 | |
| 3625516 | Handweiler et al. | Dec 1971 | |
| 3785651 | Smith | Jan 1974 | |
| 4008529 | Yorkston | Feb 1977 | |
| 4180268 | Brooks | Dec 1979 | |
| 4365438 | Nelson | Dec 1982 | |
| 4588210 | Tabatch et al. | May 1986 | |
| 4640512 | Burke | Feb 1987 | |
| 4712673 | Moore | Dec 1987 | |
| 4841911 | Houghton | Jun 1989 | |
| 4861036 | Watanabe | Aug 1989 | |
| 5226822 | Morris | Jul 1993 | |
| 5281039 | Hsiung et al. | Jan 1994 | |
| 5476264 | Ortega | Dec 1995 | |
| 5558520 | Wetzberger | Sep 1996 | |
| 5560606 | David | Oct 1996 | |
| 5732945 | Sofia | Mar 1998 | |
| 5839723 | Grimes | Nov 1998 |
| Number | Date | Country |
|---|---|---|
| 2244929 | Dec 1991 | GB |
| Entry |
|---|
| Evans, Larry; “A Super-Sneaky Double-Crossing Up, Down Round & Round Maze Book;” Klutz; © 1998. |