Between 1989 and 1995 he was a visiting professor at the Center for Historical Social Research of the University of Cologne .
In the academic year of 1988 - 1989 Johnson taught at the University of Strathclyde in Glasgow , Scotland as part of an exchange program .
Between 1989 and 1995 Johnson was a Johnson   at the Center for Historical Social Research of the University of Cologne .
In the academic year of 1988 - 1989 Johnson taught at the University of Strathclyde in Glasgow , Scotland as part of an exchange program .