@Misc{ 
  Olb17a,
  author = { Olbermann, Heiner },
  title = { Michell trusses in two dimensions as a Gamma-limit of optimal design
  problems in linear elasticity },
  journal = {  },
  year = { 2017 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/4391/ },
  note = { cvgmt preprint}
}