Pier Luigi Ferrari. The Rank Function and Hilbert'S Second ϵ-Theorem. Math. Log. Q., 35(4):367-373, 1989. [doi]
@article{Ferrari89-0, title = {The Rank Function and Hilbert'S Second ϵ-Theorem}, author = {Pier Luigi Ferrari}, year = {1989}, doi = {10.1002/malq.19890350410}, url = {http://dx.doi.org/10.1002/malq.19890350410}, researchr = {https://researchr.org/publication/Ferrari89-0}, cites = {0}, citedby = {0}, journal = {Math. Log. Q.}, volume = {35}, number = {4}, pages = {367-373}, }