@article{CTT100452720,
  author = {Eiji Watanabe and Masao Ito and Nobuo Murakoshi and AKINORI NISHIHARA},
  title = {A Synthesis of Variable Wave Digital Filters},
  journal = {IEICE Trans Fundamentals},
  year = 1994,
}

@article{CTT100691739,
  author = {Nobuo Murakoshi and Eiji Watanabe and Akinori Nishihara},
  title = {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},
  journal = {IEICE trans. fundamentals},
  year = 1993,
}