@article{SM_2000_191_2_a2,
     author = {G. A. Karpunin},
     title = {An analogue of {Morse} theory for planar linear networks and the~generalized {Steiner} problem},
     journal = {Sbornik. Mathematics},
     pages = {209--233},
     publisher = {mathdoc},
     volume = {191},
     number = {2},
     year = {2000},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_2000_191_2_a2/}
}