@article{Barmpalias2007PostSProgramme,
  year      = 2007,
  publisher = {Oxford Univ. Press},
  volume    = {17},
  number    = {6},
  pages     = {1025--1040},
  author    = {B. Afshari and G. Barmpalias and S. B. Cooper and F. Stephan},
  title     = {Post's Programme for the Ershov Hierarchy},
  journal   = {J. Log. Comput.},
}