Tin Perkov, Mladen Vukovic. Some characterization and preservation theorems in modal logic. Annals of Pure and Applied Logic, 163(12):1928-1939, 2012. [doi]
@article{PerkovV12,
title = {Some characterization and preservation theorems in modal logic},
author = {Tin Perkov and Mladen Vukovic},
year = {2012},
doi = {10.1016/j.apal.2012.07.001},
url = {http://dx.doi.org/10.1016/j.apal.2012.07.001},
researchr = {https://researchr.org/publication/PerkovV12},
cites = {0},
citedby = {0},
journal = {Annals of Pure and Applied Logic},
volume = {163},
number = {12},
pages = {1928-1939},
}