Abstract. We explore mathematical knowledge in the field of electrical engineering and claim that electrical engineering is a suitable area of application for mathematical knowledge management: We show that mathematical knowledge arising in electrical engineering can be successfully handled by existing MKM systems, namely by the Mizar system. To this end we consider in this paper network theory and in particular stability of networks. As an example for mathematical knowledge in electrical engineering we present a Mizar formalization of Schur’s theorem. Schur’s theorem provides a recursive, easy method to check for BIBO-stability of networks.