Books

1. Reciprocity Laws. From Euler to Eisenstein
2. The Correspondence between Emmy Noether and Helmut Hasse
3. I was involved in the 4th edition of Algebra I. Körper und Galoistheorie by Falko Lorenz. Additional Exercises can be downloaded from Springer's website.
4. Jacobi's lectures on ''Zahlentheorie und Kreistheilung'' (number theory and cyclotomy) from 1836/37, edited by the late H. Pieper and myself, are available from Rauner Verlag.
5. Hasse's Tagebücher (Mathematical Diaries) were published by the Universitätsverlag Göttingen
6. I also lent a helping hand to G. Frei and P. Roquette in their edition of the correspondence between Artin and Hasse. The English translation covers more letters and contains more extensive comments.
7. An introduction (in German) to the arithmetic of quadratic number fields: Quadratische Zahlkörper
8. Mathematik à la Carte I (2015) deals with elementary geometry on a level accessible to high school students.
9. 2015: Quadratic Reciprocity is an English translation of Baumgart's Thesis with a complete list of all proofs of the quadratic reciprocity law known to me.
10. 2015: The Correspondence Euler - Goldbach (Opera Omnia IV) (M. Mattmüller, F. Lemmermeyer, eds.); available online
11. 2016: The correspondence between Arnold Scholz, Helmut Hasse and Olga Taussky
12. 2016: Mathematik à la Carte II covers quadratic equations and geometric, physical and arithmetical aspects of conic sections.
13. 2017: An updated version of Quadratische Zahlkörper
14. 2021: The German translation of Jens Horyup's book Algebra in Cuneiform, Algebra in Keilschrift (together with ten of my former students).
15. 2021: Quadratic number fields; review by the MAA
16. 2022: Mathematik à la carte - Babylonische Algebra is an introduction to Babylonian algebra.
17. 2023: 4000 Jahre Zahlentheorie. Von Babel bis Abel. A history of number theory through the ages up to Abel, Jacobi and Eisenstein. A second volume will cover number theory from Kummer to Wiles.