@article{1093890707,
author = {Satre, Thomas W.},
title = {Natural deduction rules for modal logics.},
journal = {Notre Dame J. Formal Logic},
volume = {13},
number = {3},
year = {1972},
pages = { 461-475},
language = {en},
url = {http://dml.mathdoc.fr/item/1093890707}
}
Satre, Thomas W. Natural deduction rules for modal logics.. Notre Dame J. Formal Logic, Tome 13 (1972) no. 3, pp. 461-475. http://gdmltest.u-ga.fr/item/1093890707/