@article{1093891401, author = {Gleason, Gary Gilford}, title = {Normal and skew systems.}, journal = {Notre Dame J. Formal Logic}, volume = {15}, number = {1}, year = {1974}, pages = { 379-401}, language = {en}, url = {http://dml.mathdoc.fr/item/1093891401} }
Gleason, Gary Gilford. Normal and skew systems.. Notre Dame J. Formal Logic, Tome 15 (1974) no. 1, pp. 379-401. http://gdmltest.u-ga.fr/item/1093891401/