We extend Guerzhoy's Maass-modular grids on the full modular group SL₂(ℤ) to congruence subgroups Γ₀(N) and Γ₀⁺(p).
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-aa160-2-3, author = {Bumkyu Cho and SoYoung Choi and Chang Heon Kim}, title = {Harmonic weak Maass-modular grids in higher level cases}, journal = {Acta Arithmetica}, volume = {161}, year = {2013}, pages = {129-141}, zbl = {1294.11059}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-aa160-2-3} }
Bumkyu Cho; SoYoung Choi; Chang Heon Kim. Harmonic weak Maass-modular grids in higher level cases. Acta Arithmetica, Tome 161 (2013) pp. 129-141. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-aa160-2-3/