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2. J. Barwise, Back and forth thru infinitary logic, Studies in Model Theory, M.A.A., to appear.
3. J. Barwise, Admissible sets, Lecture Notes in Mathematics (Springer, Berlin) to appear.
4. The next admissible set;Barwise;J. Symb. Logic,1971
5. Some remarks on the model theory of infinitary languages;Chang,1968