@article{1093891791, author = {Girle, Roderic A.}, title = {$S\_1\not=S0.9$.}, journal = {Notre Dame J. Formal Logic}, volume = {16}, number = {1}, year = {1975}, pages = { 339-344}, language = {en}, url = {http://dml.mathdoc.fr/item/1093891791} }
Girle, Roderic A. $S_1\not=S0.9$.. Notre Dame J. Formal Logic, Tome 16 (1975) no. 1, pp. 339-344. http://gdmltest.u-ga.fr/item/1093891791/