@article{IM2_2002_66_4_a5,
     author = {K. N. Soltanov and E. B. Novruzov},
     title = {On a~free boundary problem},
     journal = {Izvestiya. Mathematics },
     pages = {807--827},
     publisher = {mathdoc},
     volume = {66},
     number = {4},
     year = {2002},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_2002_66_4_a5/}
}