| Number | Name | Date | Kind |
|---|---|---|---|
| 4508367 | Oreopoulos et al. | Apr 1985 | |
| 4511359 | Vaillancourt | Apr 1985 | |
| 4578063 | Inman et al. | Mar 1986 | |
| 4946455 | Rusen | Aug 1990 | |
| 5071413 | Utterberg | Dec 1991 | |
| 5139483 | Ryan | Aug 1992 | |
| 5158554 | Jepson et al. | Oct 1992 | |
| 5209740 | Bryant et al. | May 1993 |