K. Jaakko, Jaakko Hintikka. Identity, Variables, and Impredicative Definitions. Journal of Symbolic Logic, 21(3):225-245, 1956.
@article{JaakkoH56, title = {Identity, Variables, and Impredicative Definitions}, author = {K. Jaakko and Jaakko Hintikka}, year = {1956}, researchr = {https://researchr.org/publication/JaakkoH56}, cites = {0}, citedby = {0}, journal = {Journal of Symbolic Logic}, volume = {21}, number = {3}, pages = {225-245}, }