@article{BSL42_3-4_Kost,
author = {S{\l}awomir KOST},
title = {Countable Frames for Bimodal Logics $S5 \otimes S5$ and $Grz.3\otimes Grz.3$},
journal = {Bulletin of the Section of Logic},
volume = {42},
number = {3--4},
year = {2013},
pages = {183--198}
}