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2. Algèbre Commutative;Bourbaki,1961
3. H. Chu, The row of a matrix in E2(R[X]), in preparation.
4. On the structure of the GL2 of a ring;Cohn;Inst. Hautes Études Sci. Publ. Math.,1966
5. The construction D + XDs|X|;Costa;J. Algebra,1978