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2. Algebraic realization theory of bilinear discrete-time input-output maps;Fornasini;J. Franklin Inst.,1976
3. On the internal realization of polynomial response maps;Sontag,1976
4. Internal description of multilinear systems;Pearlman,1977
5. Pearlman J.G. & Denham M.J., Canonical realization of bilinear input/out maps, to be published.