@article{COCV_2021__27_1_A28_0,
     author = {Campbell, Daniel and Hencl, Stanislav},
     title = {Approximation of planar {Sobolev} {\protect\emph{W}\protect\textsuperscript{2,1}} homeomorphisms by piecewise quadratic homeomorphisms and diffeomorphisms},
     journal = {ESAIM: Control, Optimisation and Calculus of Variations},
     year = {2021},
     publisher = {EDP-Sciences},
     volume = {27},
     doi = {10.1051/cocv/2021019},
     language = {en},
     url = {https://www.numdam.org/articles/10.1051/cocv/2021019/}
}