@article{DCG_1991__6_4_131173,
     author = {A. Schrijver},
     title = {Disjoint {Homotopic} {Paths} and {Trees} in a {Planar} {Graph.}},
     journal = {Discrete & computational geometry},
     pages = {527--574},
     publisher = {mathdoc},
     volume = {6},
     number = {4},
     year = {1991},
     zbl = {0755.05033},
     url = {http://geodesic.mathdoc.fr/item/DCG_1991__6_4_131173/}
}