@article{AIHPC_2006__23_6_865_0,
     author = {Sz\'ekelyhidi, L\'aszl\'o},
     title = {On quasiconvex hulls in symmetric $2\times 2$ matrices},
     journal = {Annales de l'I.H.P. Analyse non lin\'eaire},
     pages = {865--876},
     publisher = {Elsevier},
     volume = {23},
     number = {6},
     year = {2006},
     doi = {10.1016/j.anihpc.2005.11.001},
     mrnumber = {2271698},
     zbl = {05138723},
     language = {en},
     url = {http://www.numdam.org/articles/10.1016/j.anihpc.2005.11.001/}
}