1. For ease of referencing, we have referred to all papers by their author and year of publication. This differs slightly from the dating system used in [15] below.
2. J. Barwise, Inflnitary Logic and Admissible Sets, Doctoral Dissertation, Stanford Univ., 1967. (Part of this appeared in J. Symbolic Logic 34 (1969), 226–252 ).
3. J. Barwise, ‘Axioms for Abstract Model Theory’, Annals of Math. Logic 1 (1974), 221–265.
4. J J. Barwise, Admissible sets and structures, Springer-Verlag, 1975.
5. J. Barwise (ed.), Handbook of Math. Logic, North-Holland, 1977.