Gillman, L.: The space $\beta N$ and the continuum hypothesis.
(English).
In:
General Topology and its Relations to Modern Analysis and Algebra.
Proceedings of the second Prague topological symposium, 1966.
Academia Publishing House of the Czechoslovak Academy of Sciences, Praha, 1967.
pp. 144-146
Gillman, L.: Remote points in $\beta R$.
(English).
In:
General Topology and its Relations to Modern Analysis and Algebra.
Proceedings of the symposium held in Prague in September 1961.
Academia Publishing House of the Czechoslovak Academy of Sciences, Prague, 1962.
pp. 175-176