@article{1093883058, author = {Tosi, P.}, title = {Normal derivability and first-order arithmetic.}, journal = {Notre Dame J. Formal Logic}, volume = {21}, number = {1}, year = {1980}, pages = { 449-466}, language = {en}, url = {http://dml.mathdoc.fr/item/1093883058} }
Tosi, P. Normal derivability and first-order arithmetic.. Notre Dame J. Formal Logic, Tome 21 (1980) no. 1, pp. 449-466. http://gdmltest.u-ga.fr/item/1093883058/