| Number | Name | Date | Kind |
|---|---|---|---|
| 2508690 | Schmerl | May 1950 | |
| 2773502 | Kaslow et al. | Dec 1956 | |
| 3155097 | Barron | Nov 1964 | |
| 3528429 | Beal | Sep 1970 | |
| 3683890 | Beal | Aug 1972 | |
| 4134405 | Smit | Jan 1979 | |
| 4239040 | Hosoya et al. | Dec 1980 | |
| 4607635 | Heyden | Aug 1986 | |
| 4637389 | Heyden | Jan 1987 | |
| 4735214 | Berman | Apr 1988 | |
| 4826485 | Johnson | May 1989 | |
| 4979947 | Berman | Dec 1990 |
| Entry |
|---|
| Richard Pulling, The Right Place, The Canadian Nurse, pp. 29-30, (Feb. 1992). |