@article{1093890999, author = {Hughes, C. E. and Singletary, W. E.}, title = {Combinatorial systems with axiom.}, journal = {Notre Dame J. Formal Logic}, volume = {14}, number = {1}, year = {1973}, pages = { 354-360}, language = {en}, url = {http://dml.mathdoc.fr/item/1093890999} }
Hughes, C. E.; Singletary, W. E. Combinatorial systems with axiom.. Notre Dame J. Formal Logic, Tome 14 (1973) no. 1, pp. 354-360. http://gdmltest.u-ga.fr/item/1093890999/