1. É. Jacquet and R. Langlands, Automorphic Forms on GL(2), Springer-Verlag (1969).
2. I. M. Gel'fand et al., Theory of Representations and Automorphisms [in Russian], Nauka, Moscow (1966).
3. M. E. Novodvorskii, Funktsional. Analiz i Ego Prilozhen.,5, No. 1, 87?88 (1971).
4. E. A. Neklyudova, Vestnik MGU,6, 72?76 (1973).