@article{10_4171_dm_7,
     author = {J\"urgen Richter-Gebert},
     title = {Two interesting oriented matroids},
     journal = {Documenta mathematica},
     pages = {137--148},
     year = {1996},
     volume = {1},
     doi = {10.4171/dm/7},
     url = {http://geodesic.mathdoc.fr/articles/10.4171/dm/7/}
}