Issued Patents 1989
Showing 1–2 of 2 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4888128 | Paper-coating slips containing fluorescent brighteners | Jochen Koll, Friedhelm Muller, Werner Bieber, Joachim Konig, Hans Theidel | 1989-12-19 |
| 4812569 | Chromogenic phthalides | — | 1989-03-14 |