@article{1093883181, author = {Hughes, G. E.}, title = {Equivalence relations and ${\rm S}5$.}, journal = {Notre Dame J. Formal Logic}, volume = {21}, number = {1}, year = {1980}, pages = { 577-584}, language = {en}, url = {http://dml.mathdoc.fr/item/1093883181} }
Hughes, G. E. Equivalence relations and ${\rm S}5$.. Notre Dame J. Formal Logic, Tome 21 (1980) no. 1, pp. 577-584. http://gdmltest.u-ga.fr/item/1093883181/