The estate of Prof. Sauer (*1898 - †1970) spans from 1933 to 1969. It includes materials related to Prof. Sauer's teaching and research activities at both the TH Aachen and the TH München. In 1937, Prof. Sauer was appointed to the professorship of applied mathematics and descriptive geometry at the TH Aachen. Due to his membership in the NSDAP and his involvement in the National Socialist German Lecturers' League, he was removed from office by the US-American occupation forces after the war. In 1948, he was appointed to the professorship of higher mathematics and analytical mechanics at the TH München. From 1954 to 1956, he served as rector of the THM and was subsequently elected pro-rector twice in the following years.