1. More on nowhere dense closed P-sets;Balcar;Bull. Acad. Pol. Sci.,1980
2. The space of ultrafilter on N covered by nowhere dense sets;Balcar;Fund. Math.,1980
3. Refinement properties and extensions of filters in Boolean algebras;Balcar;Trans. Amer. Math. Soc.,1981
4. Compact ccc non-separable spaces of small weight;Bell;Topology Proc.,1980
5. The Theory of Ultrafilters;Comfort,1974