@article{CMH_1991__66_4_140246,
     author = {P.B. Shalen and H. Gillet and R.K. Skora},
     title = {Simplicial approximation and low-rank trees.},
     journal = {Commentarii mathematici Helvetici},
     pages = {521--540},
     year = {1991},
     volume = {66},
     number = {4},
     zbl = {0794.20038},
     url = {http://geodesic.mathdoc.fr/item/CMH_1991__66_4_140246/}
}