@article{1093890711,
author = {Williamson, Colwyn},
title = {Squares of opposition: Comparisons between syllogistic and propositional logic.},
journal = {Notre Dame J. Formal Logic},
volume = {13},
number = {3},
year = {1972},
pages = { 497-500},
language = {en},
url = {http://dml.mathdoc.fr/item/1093890711}
}
Williamson, Colwyn. Squares of opposition: Comparisons between syllogistic and propositional logic.. Notre Dame J. Formal Logic, Tome 13 (1972) no. 3, pp. 497-500. http://gdmltest.u-ga.fr/item/1093890711/