1. Shellable and Cohen-Macaulay partially ordered sets;Björner;Trans. Amer. Math. Soc.,1980
2. Orderings on Coxeter groups;Björner,1984
3. An introduction to Cohen-Macaulay partially ordered sets;Björner,1982
4. Advanced Combinatorics;Comtet,1974
5. A higher invariant for matroids;Crapo;J. Combin. Theory,1967