Elements of Automorphic Representations

This is an attempt at a practical and essentially self-contained theory of automorphic representations in the framework $$L^2(\Gamma \mathrm{\backslash }\mathring{G})\text{ with }\mathring{G}=\mathring{PSL}(2,\text{B}R)\text{ and }\Gamma =\mathring{PSL}(2,\text{B}Z)\text{.}$$