1. Consistency of the unrestricted abstraction principle using an intensional equivalence operator;Aczel,1980
2. Frege structure and the notions of proposition, truth and set;Aczel,1980
3. Non-well-founded sets;Aczel,1988
4. P. Apostoli and A. Kanda. Parts of the continuum: towards. a modern ontology of science, forthcoming in The Poznan Studies in the Philosophy of Science. and the Humanities, ed. L. Nowak.
5. Approximation spaces of type-free sets;Apostoli,2000