@article{10_1090_S0894_0347_98_00277_X,
     author = {Daskalopoulos, P. and Hamilton, R.},
     title = {Regularity of the free boundary for the porous medium equation},
     journal = {Journal of the American Mathematical Society},
     pages = {899--965},
     year = {1998},
     volume = {11},
     number = {4},
     doi = {10.1090/S0894-0347-98-00277-X},
     url = {http://geodesic.mathdoc.fr/articles/10.1090/S0894-0347-98-00277-X/}
}