Abstract :
Let p > 2 be a prime, R = p[ζpf − 1], K = p[ζpf − 1], and G = SL2(pf). The group ring RG is calculated nearly up to Morita equivalence: The projections of RG into the simple components of KG are given explicitly and the endomorphism rings and homomorphism bimodules between the projective indecomposable RG-lattices are described.