Bruggeman, R. Max Planck Institute for Mathematics, Max Planck Society;
Zagier, Don Max Planck Institute for Mathematics, Max Planck Society;
Bruggeman, R., Lewis, J., & Zagier, D. (2013). Function theory related to the group PSL_2(R). In From Fourier analysis and number theory to radon transforms and geometry (pp. 107-201). Berlin [et al.]: Springer.