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[2] K. GÖDEL: The Consistency of the Axiom of Choice... Princeton (1940).

[3] P. HÁJEK, P. VOPĚNKA: Some permutation submodels of the model $\nabla $. Bull. Acad. Polon. Sci. 14 (1966) - to appear. MR 0194321

[4] T. JECH, A. SOCHOR: On $Theta $ -model of set theory. ibid. 14 (1966) - to appear. MR 0202579

[5] T. JECH, A. SOCHOR: Applications of the $Theta $ -model. ibid. 14 (1966) - to appear. Zbl 0168.01002

[6] A. LÉVY: The interdependence of certain consequences of the axiom of choice. Fundamenta Math. 54 (1964), 135-157. MR 0162705

[7] A. MOSTOWSKI: Über die Unabhängigkeit des Wohlordnungasatzes vom Ordnungsprinzip. ibid. 32 (1939), 201-252.

[8] A. MOSTOWSKI: On the principle of dependent choices. ibid. 35 (1948), 127-130. MR 0029956 | Zbl 0031.28902

[9] K. PŘÍKRÝ: The consistency of the continuum hypothedis for the first measurable cardinal. Bull. Acad. Pol. Sci. 13 (1965), 193-197. MR 0181575

[10] H. RUBIN, J. RUBIN: Equivalents of the Axiom of Choice. North-Holland Publ. Comp., Amsterdam (1963). MR 0153590 | Zbl 0129.00601

[11] E. SPECKER: Zur Axiomatik der Mengenlehre. Zeitschr. f. Math.Logik 3 (1957), 173-210. MR 0099297 | Zbl 0079.07605

[12] A. TARSKI: Axiomatic and algebraic aspects of two theorems on sums of cardinals. Fund. Math. 35 (1948), 79-104. MR 0029955 | Zbl 0031.28903

[13] P. VOPĚNKA: Předsvazek relací, Model $\nabla $. (in Czech, Presheaves of relations, the model $\nabla $), mimeographed, Prague (1964).

[14] P. VOPĚNKA: On $\nabla $ -model of set theory. Bull. Acad. Polon. Sci. 13 (1965), 267-272 . MR 0182571

[15] P. VOPĚNKA: Properties of $\nabla $ -model. ibid. 13 (1965), 441-444. MR 0189984

[16] P. VOPĚNKA, P. HÁJEK: Permutation submodels of the model $\nabla $. ibid. 13 (1965), 611-614. MR 0194320