1. On a lemma of Littlewood and Offord;Erdös;Bull. Am. Math. Soc.,1945
2. C. Greene and R. Dilworth, J. Combinatorial Theory, to appear.
3. A short proof of Sperner's lemmas;Lubell;J. Combinatorial Theory,1966
4. On Rota's problem concerning partitions;Mullin;Equationes Math.,1968
5. A generalization of Sperner's theorem, Research Problem 2-1;Rota;J. Combinatorial Theory,1967