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2. N. Jakobson, Lectures in Abstract Algebra. I, New York (1951).
3. B. Malgrange, Ideals of Differentiable Functions [Russian translation], Mir, Moscow (1968).
4. J. I. Manin, "Moduli fuchsiani," Ann. Scuola Norm. Super. Pisa,19, No. 1 (1965).