Issued Patents 1989
Showing 1–2 of 2 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4879743 | PBX and adjunct using multi-frequency tones for communication therebetween | Daniel H. Dawdy, Timothy M. Rubert | 1989-11-07 |
| 4824568 | Composite ultrafiltration membranes | Anthony E. Allegrezza, Jr. | 1989-04-25 |