1. The Foundations of Mathematics;Beth,1959
2. Church, A., 1956, Introduction to Mathematical Logic, Vol. I (Princeton)
3. The Substitution Interpretation of the Quantifiers;Dunn;Nos,1968
4. Completeness in the Theory of Types;Henkin;The Journal of Symbolic Logic,1950
5. Banishing the Rule of Substitution for Functional Variables;Henkin;The Journal of Symbolic Logic,1953