@article{GDZPPN00220360X,
title = {A free boundary problem for semilinear elliptic equations.},
journal = {Journal f\"ur die reine und angewandte Mathematik},
volume = {372},
year = {1986},
pages = {63-107},
zbl = {0598.35132},
url = {http://dml.mathdoc.fr/item/GDZPPN00220360X}
}
Alt, H.W.; Phillips, D. A free boundary problem for semilinear elliptic equations.. Journal für die reine und angewandte Mathematik, Tome 372 (1986) pp. 63-107. http://gdmltest.u-ga.fr/item/GDZPPN00220360X/