| 1980 | Habilitation, University of Essen, Germany |
| 1976 | Dr. rer. nat. (= Ph.D.), University of
Gießen, Germany
Thesis Advisor: Gerhard Michler |
| 1975 | Diplom Math. (= M.A.), University of Gießen, Germany |
| since 1989 | Professor, Temple University |
| 1987 - 1989 | Professor, Northern Illinois University |
| 1982 - 1987 | Heisenberg Research Fellow of the Deutsche
Forschungsgemeinschaft,
Max-Planck-Institut für Mathematik in Bonn, Germany |
| 1977 - 1982 | Assistent, University of Essen, Germany |
| 1976 - 1977 | Assistent (= Assistant Prof.), University of Gießen, Germany |
| 1972 - 1976 | Teaching Assistant and Instructor, University of Gießen, Germany |