Talks at colloquium in Germany
- Aachen (several times)
- Augsburg
- Berlin
- Bielefeld (several times)
- Braunschweig
- Erlangen (several times)
- Essen (several times)
- Giessen
- Heidelberg (several times)
- Jena
- Kaiserslautern (several times)
- Kassel
- Kiel
- Magdeburg
- Mainz (several times)
- Oldenburg
- Rostock
- Tübingen
Talks at colloquium abroad
- Tufts University (Boston)
- Ohio State University (Bowling Green)
- University of Chicago
- University of Illinois (Chicago) (several times)
- Ohio State University (Columbus) (several times)
- University of Oregon (Eugene)
- Michigan State University (East Lansing) (several times)
- Kansas State University (Manhattan)
- University of Wisconsin (Milwaukee)
- Rutgers University (New Brunswick) (several times)
- University of Wisconsin (Parkside)
- California Institute of Technology (Pasadena) (several times)
- University of California (Santa Cruz)
- Purdue University (West Lafayette)
- Wayne State University (Detroit)
- University of Singapore
- Tel - Aviv University (several times)
- Bar - Ilan University (Ramt Gan) (several times)
- Ben Gurion University (Beer Sheva)
- University of Triest
- University of Siena (several times)
- University of Florenz
- University of Valencia
- University of Manchester
Invited adresses
- Group Theory Meeting Durham (1978, 1990, 2001)
- Group Theory Year Rutgers University (1983)
- OSU - Debnison Conference (1984)
- DFG- Schwerpunkt Darstellungstheorie Bad Honnef (1985)
- Groups and Geometries Noordwickerhout (1986, 1989)
- 65th Birthday of D. Gorenstein (1988)
- Algebra Meeting (Novosibirsk) (1989)
- Algebraic Methods in Geometry (Vladimir) (1991)
- Special Group Theory Year (Columbus) (1995)
- AMS Annual Meeting (San Francisco) (1995)
- Groups and Geometries (Siena) (1996)
- 70th Birthday of M. Suzuki (Tokyo) (1997)
- 65th Birthday of Z. Janko (1997)
- Retirement of Bingen (Brussels) (1997)
- Groups and Geometry (Levico) (1998)
- Groups and Geometries (Bowling Green) (1999)
- Sommerschool Revision of the Classification of Finite Simple Groups
(Milano) (2000)
- Buildings and Model Theory of Groups (Würzburg)(2000)
- 70th Birthday of S. Abhyankar - Conference on Algebra and Algebraic
Geometry with Applications (West Laffayette) (2000)
- La Cave des Groupes (Lyon) (2000)
- Contributions to the study of finite simple groups (Bad Honnef) (2000)
- 65th Birthday of E. Shult (Manhattan, Kansas)(2001)
- Algebra - Geometry and Interactions (In memory of R. Baer) (Essen)
(2002)
several talks in Oberwolfach
several talks at the Baer Kolloquium
several talks at the Norddeutsche Gruppentheorie Kolloquium
several talks at Groups and Topological Groups - Meeting