| Number | Name | Date | Kind |
|---|---|---|---|
| 1832699 | Garrison | Nov 1931 | |
| 3106743 | Ellis et al. | Oct 1963 | |
| 3117827 | Cecala | Jan 1964 | |
| 3145414 | Martin | Aug 1964 | |
| 3662493 | Foltz | May 1972 |
| Entry |
|---|
| "`PH` Series Heavy Duty Exterior and Interior Floor Closure for Physically Handicapped Access," Rirson-Fire Mark undated PPG Industries May, 1984 product catalog for Architectural Metals, pp. C-3 and C-4. |