Conversation so far:
Where did Bernard Lewis go to school?
He attended the School of Oriental Studies at the University of London.
What did Bernard Lewis study?
Bernard Lewis graduated from the School of Oriental Studies at the University of London with a BA in history with special reference to the Near and Middle East.
Did Bernard Lewis study anywhere else besides the School of Oreintal Studies?
Bernard Lewis undertook post-graduate studies at the University of Paris.
When did Bernard Lewis study at the University of Paris?
Bernard Lewis undertook post-graduate studies at the University of Paris, where he studied with the orientalist Louis Massignon and earned the Diplôme des Études Sémitiques in 1937.
Was University of Paris the last place Bernard Lewis went to study?
Bernard Lewis returned to School of Oriental Studies in 1938 as an assistant lecturer in Islamic History.

Question: How long was he there for?
Self-contained rewrite: How long Bernard Lewis at the School of Oriental Studies for?