After his return to Harvard University, he had the privilege of being selected as a fellow of the Byzantine Studies Foundation of Harvard University, Dumbarton Oaks, where he remained for three years. During his stay at this internationally renowned Study Center, he had the valuable opportunity not only to use its excellent library but also to collaborate with prominent personalities of the scientific world, such as Francis Dvornik, Ernst Kitzinger, Milton Anastos, John Meyendorff, etc.

Within such a favorable scientific environment, he continued to work on his doctoral thesis for Harvard University.