Issued Patents 1989
Showing 1–1 of 1 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4815895 | Construction of tunnels or pipes for use in civil engineering works | Robert D. Porteous | 1989-03-28 |
Showing 1–1 of 1 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4815895 | Construction of tunnels or pipes for use in civil engineering works | Robert D. Porteous | 1989-03-28 |