@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}},
  extra_urls= {{https://www.researchgate.net/publication/268979991_Reflecting_on_the_3x_1_Mystery_Outline_of_a_Scenario_-_Improbable_or_Realistic}},
}