@article{MAN_1993__297_3_165124,
     author = {W. Hansen and N. Nadirashvili},
     title = {Mean values and harmonic functions.},
     journal = {Mathematische Annalen},
     pages = {157--170},
     publisher = {mathdoc},
     volume = {297},
     number = {3},
     year = {1993},
     zbl = {0794.31002},
     url = {http://geodesic.mathdoc.fr/item/MAN_1993__297_3_165124/}
}