1. Of Propositions Numerically Definite, 1868;Boole,1952
2. On a Combinatorial Problem;de;Nederl. Akad. v. Wetensch.,1948
3. The Complexity of Theorem Proving Procedures;Cooke,1970
4. The Representation of a Graph by Set Intersections;Erdös;Canad. J. Math.,1966
5. A Problem in Partitions;Hall;Bull. Amer. Math. Soc.,1941