1. [Bl] Blass, A.: Simple cardinal invariants. (preprint)
2. [v Do] van Douwen, E.K.: The integers and topology. In: Kunen, K., Vaughan, J.E. (eds.) Handbook of Set-Theoretic Topology. North-Holland: Amsterdam New York Oxford 1984
3. [CN] Comfort, W.W., Negrepontis, S.: Theory of ultrafilters. Berlin Heidelberg New York: Springer 1974
4. [Mi] Miller, A.: Some properties of measure and category. Trans. Am. Math. Soc.266, 93?114 (1981)
5. [Sh 470] Shelah, S.: Vive la difference! In: Judah, H., Just, W., Woodin, W.H. (eds.) Proceedings of the MSRI Logic Year 1989/90