(1) Introduction to Axiomatic Set Theory; Jean-Louis Krivine; Humanities Press, 1971 (2) Set Theory; T. Jech; Springer, 1997 (3) Set Theory and the Continuum Hypothesis; Paul Cohen; W.A. Benjamin, 1966 (4) Set Theory and the Continuum Problem; R. Smullyan and M. Fitting; Clarendon Press, 1996 (5) Theory of Sets; E. Kamke; Dover, 1950 (6) An Introduction to Hilbert Space; N. Young; Cambridge University Press, 1988 (7) The Continuum and Other Types of Serial Order; E.V. Huntington; Dover, 1955 (8) Contributions to the Founding of the Theory of Transfinite Numbers; Georg Cantor; Dover, 1915 s