Jack Hoeksema hoeksema@nl.rug.let University of Groningen " > Universiteitskrant (UK) of the University of Groningen 1990/1991 and 1991/1992. " > Universiteitskrant (UK) of the University of Groningen 1990/1991 and 1991/1992. " > Universiteitskrant (UK) of the University of Groningen 1990/1991 and 1991/1992. " > Universiteitskrant (UK) of the University of Groningen 1990/1991 and 1991/1992. " >