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Families of $\phi$-congruence subgroups of the modular group. (arXiv:2206.12442v1 [math.NT]) http://arxiv.org/abs/2206.12442
Families of $\phi$-congruence subgroups of the modular group. (arXiv:2206.12442v1 [math.NT]) http://arxiv.org/abs/2206.12442