Before revision: In electronic circuit theory the process of network synthesis from transfer functions, which led to electronic circuits being regarded as " bla9-X , page xi</ref> black boxes" characterized by their response to signals applied to their ports, can be traced to Wilhelm Cauer who published his ideas in their most developed form in 1941.Cauer, Wilhelm; Theorie der linearen Wechselstromschaltungen, Vol.I, Akademische Verlags-Gesellschaft Becker und Erler, Leipzig, 1941.
After revision: In electronic circuit theory the process of network synthesis from transfer functions, which led to electronic circuits being regarded as " black boxes" characterized by their response to signals applied to their ports, can be traced to Wilhelm Cauer who published his ideas in their most developed form in 1941.Cauer, Wilhelm; Theorie der linearen Wechselstromschaltungen, Vol.I, Akademische Verlags-Gesellschaft Becker und Erler, Leipzig, 1941.