Issued Patents All Time
Showing 1–2 of 2 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4247221 | Process for lining tunnels | Hans Lewer, Gunter Seifert | 1981-01-27 |
| 4190292 | Process for suppressing dust in mines | Harald Johannes, Gunther SEIFERT, Hans Lewer | 1980-02-26 |