@article{IM2_2011_75_5_a1,
     author = {P. A. Borodin},
     title = {On the convexity of $N${-Chebyshev} sets},
     journal = {Izvestiya. Mathematics },
     pages = {889--914},
     publisher = {mathdoc},
     volume = {75},
     number = {5},
     year = {2011},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_2011_75_5_a1/}
}