1. Distributive Lattices;Balbes,1974
2. Modal Logic;Chagrov,1997
3. On the connection of partially ordered sets with some pseudo-Boolean algebras;de Jongh;Indag. Math.,1966
4. The degrees below a 1-generic degree <0′;Haught;J. Symbolic Logic,1986
5. A survey of Mučnik and Medvedev degrees;Hinman;Bull. Symbolic Logic,2012