Issued Patents 1989
Showing 1–2 of 2 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4880066 | Assembly for directional drilling of boreholes | Abe Steiginga | 1989-11-14 |
| 4836301 | Method and apparatus for directional drilling | Johannes Cornelis Maria Van Dongen | 1989-06-06 |