@article{SLC_1987_18_a1,
     author = {Andreas Dress and Walter Wenzel},
     title = {Matroids with {Coefficients}},
     journal = {S\'eminaire lotharingien de combinatoire},
     year = {1987},
     volume = {18},
     url = {http://geodesic.mathdoc.fr/item/SLC_1987_18_a1/}
}