"Eiji Watanabe,Masao Ito,Nobuo Murakoshi,AKINORI NISHIHARA","A Synthesis of Variable Wave Digital Filters",,"IEICE Trans Fundamentals",,"Vol. E77","No. 1","pp. 263-271",1994,Jan.
"Nobuo Murakoshi,Eiji Watanabe,Akinori Nishihara","A Synthesis of Complex Allpass Circuits Using the Factorization of Scattering Matrices --- Explicit Formulae for Even-Order Real Complementary Filters Having Butterworth or Chebyshev Responses",,"IEICE trans. fundamentals",,"Vol. E76-A","No. 3","pp. 317-325",1993,Mar.