@incollection{Barmpalias2017NoteDifferencesComputably,
  year      = 2016,
  publisher = {Springer},
  pages     = {623--632},
  author    = {G. Barmpalias and A. Lewis-Pye},
  title     = {A Note on the Differences of Computably Enumerable Reals},
  booktitle = {Computability Complexity},
}