From 1496 to 1500 he was at the University of Cologne.

The University of Cologne alone has more than 50,000 students.

He became a professor at the University of Cologne in 1930.

In the same year the University of Cologne was closed.

After the war, he became a professor at the University of Cologne in 1945.

He held a chair for economic policy at the University of Cologne until 2009.

From 1961 to 1963 he studied at the University of Cologne.

He studied law at the University of Cologne from 1968 to 1973.

In the same year he was also appointed as professor for public and international law at Cologne University.

It was purchased by the University of Cologne in 1969.