@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/