@article{BSL1_1_Surma1,
author = {Stanis{\l}aw J. SURMA},
title = {The Deduction Theorems Valid in Certain Fragments of the Lewis' System S2 and the System of Feys-Von Wright},
journal = {Bulletin of the Section of Logic},
volume = {1},
number = {1},
year = {1972},
pages = {45--52}
}