@article{LJM_2000_6_a0,
     author = {A. Addou and S. Lahrech},
     title = {Sufficient conditions for elliptic problem of optimal control in~$\mathbb R^2$},
     journal = {Lobachevskii journal of mathematics},
     pages = {3--17},
     publisher = {mathdoc},
     volume = {6},
     year = {2000},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/LJM_2000_6_a0/}
}