Poincaré series in SL(3, R)

It is shown that in the spectral decomposition of the one-parameter Poincaré series from SL(3, R) involves only the discrete spectrum, induced from SL₂ and not the discrete spectrum of SL₃ itself. Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 160, pp. 37–40, 1987.