sentences:  Kitzinger quickly advanced through the ranks at Dumbarton Oaks, becoming an Assistant Professor in 1946, Associate Professor in 1951, Director of Studies in 1955, and Professor of Byzantine Art and Archaeology in 1956.As Director of Studies he firmly established Dumbarton Oaks as an academic institution of international renown and the world's leading institution for Byzantine studies.Kitzinger resigned as director of studies at Dumbarton Oaks in 1966, in part to rebalance his work as a scholar after eleven years of heavy administrative duties.