1. More on nowhere dense closed P-sets;Balcar;Bull. Acad. Polon. Sci.,1980
2. The space of ultrafilters 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. Embedding of Boolean algebras in P(w)/fin;Baumgartner;Fund. Math.,1990
5. Almost disjoint refinement of families of subsets of N;Balcar;Proc. Amer. Math. Soc.,1980