@article{3300, author = {Figallo, Aldo V.}, title = {On the congruences in four-valued modal algebras}, journal = {Portugaliae mathematica}, volume = {49}, year = {1992}, pages = {249-261}, zbl = {0787.03060}, mrnumber = {1201977}, language = {en}, url = {http://dml.mathdoc.fr/item/3300} }
Figallo, Aldo V. On the congruences in four-valued modal algebras. Portugaliae mathematica, Tome 49 (1992) pp. 249-261. http://gdmltest.u-ga.fr/item/3300/