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Continuity of intersection of analytic sets P. Tworzewski, T. Winiarski (1983) Annales Polonici Mathematici
Convergence Sets of a Formal Power Series. N. Levenberg, R.E. Molzon (1988) Mathematische Zeitschrift
Convergence sets of divergent power series. Avinash Sathaye (1976) Journal für die reine und angewandte Mathematik