Berchio, Elvise, Filippo Gazzola and Tobias Weth. "Radial symmetry of positive solutions to nonlinear polyharmonic Dirichlet problems" Journal für die reine und angewandte Mathematik (Crelles Journal), 2008.620 (2008): 165-183. Retrieved 19 May. 2013, from doi:10.1515/CRELLE.2008.052

Berchio, E., Gazzola, F. & Weth, T. (2008). Radial symmetry of positive solutions to nonlinear polyharmonic Dirichlet problems. Journal für die reine und angewandte Mathematik (Crelles Journal), 2008(620), pp. 1-233. Retrieved 19 May. 2013, from doi:10.1515/CRELLE.2008.052

Berchio, Elvise, Filippo Gazzola and Tobias Weth. 2008. Radial symmetry of positive solutions to nonlinear polyharmonic Dirichlet problems. Journal für die reine und angewandte Mathematik (Crelles Journal). 2008(620): 1-233. Retrieved 19 May. 2013, from doi:10.1515/CRELLE.2008.052