Jeffry L. Hirst. Hindman s theorem, ultrafilters, and reverse mathematics. Journal of Symbolic Logic, 69(1):65-72, 2004. [doi]
@article{Hirst04-0, title = {Hindman s theorem, ultrafilters, and reverse mathematics}, author = {Jeffry L. Hirst}, year = {2004}, url = {http://projecteuclid.org/euclid.jsl/1080938825}, researchr = {https://researchr.org/publication/Hirst04-0}, cites = {0}, citedby = {0}, journal = {Journal of Symbolic Logic}, volume = {69}, number = {1}, pages = {65-72}, }