Complex sentence: He became an Assistant in course teaching at Erlangen for five years (1957-1961) and, following his marriage, returned to his former University as Lecturer for another five years (until 1966).
Split into simpler sentences: He became an Assistant in course teaching at the University Erlangen for five years (1957-1961). After his marriage which followed, returned to his former University to be placed Lecturer for another five years (till 1966).