1. On Boundary Numbers and Domains of Sets: New Investigations in the Foundations of Set Theory;Zermelo;From Kant to Hilbert,1930
2. Investigations into the Foundations of Set Theory I;Zermelo;From Frege to Gödel,1908
3. Is It Too Much to Ask, to Ask for Everything?;Weir;Absolute Generality
4. Über eine Widerspruchfreiheitsfrage in der axiomatischen Mengenlehre;von Neumann;Collected Works,1929