@article{1093893940, author = {Gregg, John R.}, title = {Axiomatic quasi-natural deduction.}, journal = {Notre Dame J. Formal Logic}, volume = {11}, number = {1}, year = {1970}, pages = { 221-228}, language = {en}, url = {http://dml.mathdoc.fr/item/1093893940} }
Gregg, John R. Axiomatic quasi-natural deduction.. Notre Dame J. Formal Logic, Tome 11 (1970) no. 1, pp. 221-228. http://gdmltest.u-ga.fr/item/1093893940/