%0 Book Section %A Koecher, Max %A Krieg, Aloys %T Geometry in the upper half-plane and the action of the modular group %C Berlin, Heidelberg %I Springer Berlin Heidelberg %M RWTH-2026-02726 %B Universitext %P 109-152 %D 2025 %< Elliptic Functions and Modular Forms / Max Koecher, Aloys Krieg %F PUB:(DE-HGF)7 %9 Contribution to a book %R 10.1007/978-3-662-71224-5_2 %U https://publications.rwth-aachen.de/record/1030034