@article{zajíček_2007, 
  title={On sets of non-differentiability of Lipschitz and convex functions}, 
  volume={132}, 
  DOI={10.21136/mb.2007.133997}, 
  publisher={Institute of Mathematics, Czech Academy of Sciences}, 
  author={Zajíček, Luděk}, 
  year={2007}
  }