Complex sentence: In 1938, Celan travelled to Tours, France, to study medicine (the newly-imposed Jewish quota in Romanian universities and the Anschluss precluded Bucharest and Vienna), but returned to Cernăuţi in 1939 to study literature and Romance languages.
Split into simpler sentences: In 1938, Celan travelled to Tours, France, to study medicine. But returned to Cernăuţi in 1939 to study literature and Romance languages.