@article{JAC_2009__30_2_a4,
     author = {Postnikov, Alexander and Speyer, David and Williams, Lauren},
     title = {Matching polytopes, toric geometry, and the totally non-negative {Grassmannian}},
     journal = {Journal of Algebraic Combinatorics},
     pages = {173--191},
     publisher = {mathdoc},
     volume = {30},
     number = {2},
     year = {2009},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JAC_2009__30_2_a4/}
}