Dilip Raghavan, Stevo Todorcevic. Cofinal types of ultrafilters. Annals of Pure and Applied Logic, 163(3):185-199, 2012. [doi]
@article{RaghavanT12, title = {Cofinal types of ultrafilters}, author = {Dilip Raghavan and Stevo Todorcevic}, year = {2012}, doi = {10.1016/j.apal.2011.08.002}, url = {http://dx.doi.org/10.1016/j.apal.2011.08.002}, researchr = {https://researchr.org/publication/RaghavanT12}, cites = {0}, citedby = {0}, journal = {Annals of Pure and Applied Logic}, volume = {163}, number = {3}, pages = {185-199}, }