During the period 1939-1942, he published the "Goethe and Schiller in Weimar" (Berlin, 1941), "Theodore Kyorner and Hristo Botev" (Berlin, Sofia, 1942), "Die politische Entwickling Bulgariens" (Budapest, 1942) in German and "L'Eterno nel dirito naturale" (Roma, 1940) in Italian.
