1. Reduced products;Frayne;A.M.S. Notices,1958
2. Model theoretic properties of reduced products;Frayne;A.M.S. Notices,1958
3. Les classes definissables d’algebras, Mathematical Interpretations of Formal Systems;Łoś,1955
4. Peano’s axioms and models of arithmetic;Skolem,1955
5. Sur la decomposition des ensembles en sous-ensembles presque disjoints;Tarski;Fund. Math.,1928