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The consistency of the axiom of choice and of the generalized continuum hypothesis with the axioms of set theory. Annals of Math. Studies 3, Princeton 1940.
MR 0024870
[2] P. VOPĚNKA:
Properties of $\nabla $ -model. Bull. Acad. Sci. Polon 13 (1965).
MR 0189984
[3] P. VOPĚNKA:
$\nabla $ -models in which the generalized continuum hypothesis does not hold. Bull. Acad. Sci. Polon 13 (1965).
MR 0182570