1. The space of ultrafilters on N covered by nowhere dense sets;Balcar;Fund. Math.,1980
2. Cardinal invariants in Boolean spaces;Balcar;Proceedings 5th Prague Topology Symposium,1981
3. Iterated perfect-set forcing;Baumgartner;Ann. Math. Logic,1979
4. Spaces co-absolute with βN − N;Broverman;Topology Appl.,1981
5. E. Coplakova and P. Vojtas, A new sufficient condition for the existence of Q-points in βω − ω, preprint.