1. D. Borthwick, C. Judge and P. Perry, Selberg’s zeta function and the spectral geometry of geometrically finite hyperbolic surfaces, Comment. Math. Helv. 80 (2005), 483–515.
2. R. Boas, Entire Functions, Academic Press, New York, 1954.
3. D. Borthwick, Spectral Theory of Infinite-area Hyperbolic Surfaces, Birkhäuser/Springer, Cham, 2016.
4. M. Doll, K. Fedosova and A. Pohl, Counting resonances on hyperbolic surfaces with unitary twists, arXiv:2109.12923 [math.SP]
5. NIST Digital Library of Mathematical Functions, Release 1.1.3 of 2021-09-15 http://dlmf.nist.gov/.