@incollection{Belaga1998,
  author    = {{Edward Belaga}},
  title     = {{Reflecting on the $3x+1$ Mystery: Outline of a Scenario- Improbable or Realistic?}},
  booktitle = {{U. Strasbourg report}},
  year      = {{1998}},
  url       = {{http://hal.archives-ouvertes.fr/IRMA-ACF, file hal-0012576}},
}