@article{MS2_1977__41_166555,
     author = {A.B. Hansen},
     title = {On a certain class of polytopes associated with independence systems.},
     journal = {Mathematica Scandinavica},
     pages = {225--241},
     publisher = {mathdoc},
     volume = {41},
     year = {1977},
     zbl = {0411.05033},
     url = {http://geodesic.mathdoc.fr/item/MS2_1977__41_166555/}
}