1. [Sh] G. Shimura, Introduction to the arithmetic theory of automorphic functions, Publications of the Mathematical Society of Japan, No. 11. Iwanami Shoten, Publishers, Tokyo, 1971.
2. [AS] A. Ash and G. Stevens, Cohomology of arithmetic groups and congruences between systems of Hecke eigenvalues, J. Reine Angew. Math. 365 (1986), 192–220.
3. [A] A. Ash, Farrell cohomology of $\rm GL(n,\bf Z)$, Israel J. Math. 67 (1989), no. 3, 327–336.
4. [AGG] A. Ash, D. Grayson, and P. Green, Computations of cuspidal cohomology of congruence subgroups of $\rm SL(3,\bf Z)$, J. Number Theory 19 (1984), no. 3, 412–436.
5. [AM] A. Ash and McConnell, $\Mod p$ cohomology of $SL(n,\mathbbZ)$, preprint.