@article{SIGMA_2007_3_a52,
     author = {Yuri Bozhkov and Enzo Mitidieri},
     title = {Lie {Symmetries} and {Criticality} of {Semilinear} {Differential} {Systems}},
     journal = {Symmetry, integrability and geometry: methods and applications},
     year = {2007},
     volume = {3},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SIGMA_2007_3_a52/}
}