@article{EJDE_2015__2015__a15,
     author = {Liu, Wei and Jia, Gao and Guo, Lu-Quian},
     title = {Multiplicity of solutions to the sum of polyharmonic equations with critical {Sobolev} exponents},
     journal = {Electronic Journal of Differential Equations},
     publisher = {mathdoc},
     volume = {2015},
     year = {2015},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/EJDE_2015__2015__a15/}
}