1. K.J. Barwise, Back and forth through infinitary logic, in: Studies in Model Theory, MAA Studies vol. 8, 1973, 5–34.
2. M. Benda, Reduced products and nonstandard logics, Journal of Symbolic Logic 34(1969), 424–436.
3. J.-P. Calais, Partial isomorphisms and infinitary languages, Zeitschrift für Math. Logik 18(1972), 435–456.
4. G. Cantor, Contributions to the Founding of the Theory of Transfinite Numbers, Dover Publ. Co., New York.
5. C.C. Chang, Some remarks on the model theory of infinitary lanquages, in: The Syntax and Semantics of Infinitary Languages, Springer-Verlag, Berlin, 1968, 36–63.