1. W. Ackermann. Solvable Cases of the Decision Problem. North-Holland, Amsterdam, 1962.
2. P. Aczel. Non-well-founded Sets. CSLI, Stanford CA, 1988.
3. J. E. J. Altham and N. W. Tennant. Sortal quantification. In E. L. Keenan, editor, Formal Semantics of Natural Language, pages 46–58. Cambridge University Press, 1975.
4. J. M. Anderson and H. W. Johnstone Jr. Natural Deduction: The Logical Basis of Axiom Systems. Wadsworth, Belmont, CA., 1962.
5. J. Ax and S. Kochen. Diophantine problems over local fields: I. American Journal of Mathematics, 87:605–630, 1965.