Symplectic periods. Hervé Jacquet, Stephen Rallis (1992) Journal für die reine und angewandte Mathematik
Symplectic periods of the continuous spectrum of GL ( 2 n ) Shunsuke Yamana (2014) Annales de l’institut Fourier We provide a formula for the symplectic period of an Eisenstein series on GL ( 2 n ) and determine when it is not identically zero.