@Misc{ 
  dem07,
  author = { Demyanov, Alexey },
  title = { Regularity of stresses in Prandtl-Reuss perfect plasticity },
  journal = {  },
  year = { 2007 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/1627/ },
  note = { cvgmt preprint}
}