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2. Corners and arithmetic groups;Borel, A.;Comment. Math. Helv.,1973
3. Publications de l'Institut de Math\'{e}matique de l'Universit\'{e} de Strasbourg, XV. Actualit\'{e}s Scientifiques et Industrielles, No. 1341;Borel, Armand,1969
4. Non-square-integrable cohomology of arithmetic groups;Ash, Avner;Duke Math. J.,1980