@article{M2AN_2008__42_6_925_0,
     author = {Buffa, Annalisa and Monk, Peter},
     title = {Error estimates for the ultra weak variational formulation of the {Helmholtz} equation},
     journal = {ESAIM: Mod\'elisation math\'ematique et analyse num\'erique},
     pages = {925--940},
     publisher = {EDP-Sciences},
     volume = {42},
     number = {6},
     year = {2008},
     doi = {10.1051/m2an:2008033},
     mrnumber = {2473314},
     zbl = {1155.65094},
     language = {en},
     url = {http://archive.numdam.org/articles/10.1051/m2an:2008033/}
}