He also worked as a guest professor or speaker at several universities outside of China.

In 1946, he returned to Cologne to work as a guest professor.

Archer moved there in 1960 as a guest professor to find two opposing belief systems.

He served as guest professor at Harvard University during 1907-1908.

Instead, he was welcomed as a guest professor in the young republic of Indonesia during the academic year 1951-1952.

He is a guest professor of several universities in China and Japan.

He was an internationally known author, lecturer, and guest professor in the field of ethics.

Each term, several of these experts from Switzerland and abroad are engaged as guest professors.

In 1978 and 1979 he was a guest professor at the University of Siegen.

He spent one year as a guest professor at the University of Tromsø.