@article{ASNSP_1998_4_26_3_507_0,
     author = {Gustafsson, Bj\"orn and Putinar, Mihai},
     title = {An exponential transform and regularity of free boundaries in two dimensions},
     journal = {Annali della Scuola Normale Superiore di Pisa - Classe di Scienze},
     pages = {507--543},
     publisher = {Scuola normale superiore},
     volume = {Ser. 4, 26},
     number = {3},
     year = {1998},
     mrnumber = {1635702},
     zbl = {0937.32007},
     language = {en},
     url = {http://www.numdam.org/item/ASNSP_1998_4_26_3_507_0/}
}