@article{BSL3_2_Wronski,
author = {Stanis{\l}aw J. SURMA and Andrzej WRO{\'N}SKI, and Stanis{\l}aw ZACHOROWSKI},
title = {On Equivalential Fragments of Some Intermediate Logics},
journal = {Bulletin of the Section of Logic},
volume = {3},
number = {2},
year = {1974},
pages = {11--14}
}