1. de BRUIN, M.G. and van ROSSUM, H. Formal Padé-approximation. Nieuw Archief voor Wiskunde (3), 23, 1975, pp. 115–130.
2. GODEMENT, R. Algebra. Kershaw Publ. Co. Ltd., London, 1969.
3. KARLSSON, J. and WALLIN, H. Rational approximation by an interpolation procedure in several variables. In: Staff, E.B. and Varga, R.S. Padé and rational approximation: theory and appl. Academic Press, London, 1977, pp. 83–100.
4. LARSEN, R. Banach-Algebras, an introduction. Marcel Dekker, Inc. New York, 1973.
5. RALL, L.B. Computational Solution of Nonlinear Operator Equations. J. Wiley and Sons. New York, 1969.