@Article{ 
  caggomtraa,
  author = { Cagnetti, Filippo and Gomes, Diogo and Tran, Hung V. },
  title = { Adjoint Methods for Obstacle Problems and Weakly Coupled Systems of PDE },
  journal = { ESAIM Control Optim. Calc. Var. },
  year = { 2013 },
  volume = { 19 },
  pages = { 754-779 },
  URL = { http://cvgmt.sns.it/paper/1252/ },
  note = { cvgmt preprint}
}