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2. Lecture Notes in Mathematics;A. Bak,1969
3. A. Bak, K-Theory of Forms, Annals of Mathematics Studies 98, Princeton University Press, 1981.
4. A. Bak, Le probleme des sous-groupes de congruence et le probleme metaplectique pour les groupes classiques de rang >1, C.R. Acad. Sc. Paris, 292, 307–310 (1981).
5. A. Bak and U. Rehann, The congruence subgroup and metaplectic problems for SLN>2 of division algebras, J. Algebra, 78 (1982), 475–547.