@article{ZNSL_1997_246_a1,
     author = {M. L. Egorov and V. A. Zalgaller},
     title = {Visibility curves for ovals},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {13--35},
     publisher = {mathdoc},
     volume = {246},
     year = {1997},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1997_246_a1/}
}