@Article{Hla92d,
  author	= {F. Hlawatsch},
  title		= {Regularity and unitarity of bilinear time-frequency signal representations},
  journal	= {IEEE Trans. Inf. Theory},
  year		= {1992},
  month		= {Jan.},
  volume	= {38},
  number	= {1},
  pages		= {82--94}
}