His thesis Die Grundlagen der ägyptischen Bruchrechnung ("The Fundamentals of Egyptian Calculation with Fractions") (Springer, 1926) was a mathematical analysis of the table in the Rhind Papyrus. In 1927, he received his venia legendi for the history of mathematics and served as Privatdozent. In 1927, his first paper on Babylonian mathematics was an account of the origin of the sexagesimal system.