| 2015- | Professor emeritus, Johannes Gutenberg--Universität, Mainz |
| 1992-2015 | Professor für Geschichte der Mathematik und der Naturwissenschaften, JGU, Mainz |
| 1990-1992 | Professor, Pace University, Pleasantville, New York |
| 1988-1990 | Associate Professor, Pace University |
| 1982-1988 | Assistant Professor, Pace University |
| 1981-1982 | Adjunct Assistant Professor, Fordham University and Lehman College, CUNY |