Hilary Putnam. Trial and Error Predicates and the Solution to a Problem of Mostowski. Journal of Symbolic Logic, 30(1):49-57, 1965.
@article{Putnam65, title = {Trial and Error Predicates and the Solution to a Problem of Mostowski}, author = {Hilary Putnam}, year = {1965}, researchr = {https://researchr.org/publication/Putnam65}, cites = {0}, citedby = {0}, journal = {Journal of Symbolic Logic}, volume = {30}, number = {1}, pages = {49-57}, }