[1] W. W. COMFORT S. NEGREPONTIS: The theory of ultrafliters. Springer-Verlag 1974. MR 0396267

[2] R. ENGELKING: General Topology. Warszawa 1977. MR 0500780 | Zbl 0373.54002

[3] A. M. GLEASON: Projective topological spaces. Illinois J. Math. 2 (1958), 482-489. MR 0121775 | Zbl 0083.17401

[4] J. MIODUSZEWSKI: On a method which leads to extremally disconnected covers. Proceedings of the Third Prague Topological Symposium 1971, Academia Prague 1972, 309-311. MR 0362197

[5] V. I. PONOMAREV L. B. ŠAPIRO: Absolutes of topological spaces and their continuous maps. Uspekhi Math. 31 (1976), 121-136. MR 0451216

[6] R. G. WOODS: A survey of absolutes of topological spaces. Topological Structures II, Part 2, Proceedings of the Symposium in Amsterdam 1978, 323-362. MR 0565852