1989 "Boundaries, organizations and change", Amsterdam may 30 - june 1, 1989.

1989 "Chaos and constructions in companies", Leusden, november, 22-25, 1989.

1990 "Chaos and constructions in companies", Leusden, may 31 - june 1, 1990.

1990 "Zelf-organisatie en chaos in bedrijven", Amsterdam, october 26, 1990. (publication appeared as 1990e)

1990 "Zelf-organisatie in bedrijven", 5 invited lectures for the Faculty of Business Administration, Rijksuniversiteit Groningen.

1991 "Radical change processes in the self-organizing business system", Leusden, march 6-8, 1991.

1991 "Management tussen postmodern en zelf-organiserend", Amsterdam, may 29, 1991.