@Article{ BraDefVit97, author = { Andrea Braides and Anneliese Defranceschi and Enrico Vitali }, title = { A relaxation approach to Hencky's plasticity }, journal = { Applied Math. Optim. }, year = { 1997 }, doi = { 10.1007/BF02683319 }, volume = { 35 }, pages = { 45-68 }, }