@article{10_4064_am38_3_2,
     author = {Jaros{\l}aw L. Bojarski},
     title = {Regularity of displacement solutions
 in {Hencky} plasticity.
 {I:} {The} extremal relation},
     journal = {Applicationes Mathematicae},
     pages = {259--293},
     publisher = {mathdoc},
     volume = {38},
     number = {3},
     year = {2011},
     doi = {10.4064/am38-3-2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/am38-3-2/}
}