Balder ten Cate, David Gabelaia, Dmitry Sustretov. Modal languages for topology: Expressivity and definability. Annals of Pure and Applied Logic, 159(1-2):146-170, 2009. [doi]
@article{CateGS09,
title = {Modal languages for topology: Expressivity and definability},
author = {Balder ten Cate and David Gabelaia and Dmitry Sustretov},
year = {2009},
doi = {10.1016/j.apal.2008.11.001},
url = {http://dx.doi.org/10.1016/j.apal.2008.11.001},
researchr = {https://researchr.org/publication/CateGS09},
cites = {0},
citedby = {0},
journal = {Annals of Pure and Applied Logic},
volume = {159},
number = {1-2},
pages = {146-170},
}