1. Homology of matroids;Björner,1979
2. Homotopy properties of greedoids;Björner;Adv. Appl. Math.,1985
3. Topological methods;Björner,1989
4. The homology and shellability of matroids and geometric lattices;Björner,1992
5. Which spheres are shellable?;Danaraj;Ann. Discrete Math.,1978