@article{EJDE_2001__2001__a210,
     author = {Amdeberhan,  Tewodros},
     title = {Two symmetry problems in potential theory},
     journal = {Electronic journal of differential equations},
     year = {2001},
     volume = {2001},
     zbl = {0981.35045},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/EJDE_2001__2001__a210/}
}