1. A decomposition theorem for partially ordered sets;Dilworth;Ann. of Math.,1950
2. The structure of Sperner k-familes;Greene;J. Combinatorial Theory A,1976
3. Some partitions associated with a partially ordered set;Greene;J. Combinatorial Theory A,1976
4. On partitions of a partially ordered set;Hoffman;J. Combinatorial Theory B,1977
5. Transversal Theory;Mirsky,1971