@article{MO_2004_1_a2,
     author = {A. I. Schetnikov},
     title = {A {Sum} of {Angles} of a {Self-intersecting} {Polygon}},
     journal = {Matemati\v{c}eskoe obrazovanie},
     pages = {78--86},
     year = {2004},
     number = {1},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MO_2004_1_a2/}
}