New interest in modular forms of one complex variable has been caused
chiefly by the work of Selberg and of Eichler. But there has been no
introductory work covering the background of these developments. H. C.
Gunning's book surveys techniques and problems; only the simpler cases
are treated-modular forms of even weights without multipliers, the
principal congruence subgroups, and the Hecke operators for the full
modular group alone.