sentences:  Ritzen worked as a civil engineering consultant in Bangladesh from August 1976 until April 1978 and as a visiting professor of Education economics at the University of California, Berkeley from September 1978 until May 1979.Ritzen worked as an associate professor of Public economics at the Radboud University Nijmegen from May 1978 until January 1981 and a professor of Education economics at the Erasmus University Rotterdam from January 1981 until September 1982.Ritzen worked as a political consultant for the Labour Party from September 1982 until November 1989 and also as science advisor for the Leader of the Labour Party and Parliamentary leader of the Labour Party in the House of Representatives Joop den Uyl from September 1982 until July 1986.