@incollection{Wirsching2001,
  author    = {{Wirsching, Günther J.}},
  title     = {{A functional differential equation and $3n + 1$ dynamics}},
  booktitle = {{Topics in Functional Differential and Functional Difference Equations (Lisbon 1999)}},
  publisher = {{Amer. Math. Soc.}},
  year      = {{2001}},
  volume    = {{29}},
  pages     = {{369--378}},
  note      = {{MR 2002b:11035}},
}