@article{1183731783, author = {Fitch, Frederic B.}, title = {A Definition of Negation in Extended Basic Logic}, journal = {J. Symbolic Logic}, volume = {19}, number = {1}, year = {1954}, pages = { 29-36}, language = {en}, url = {http://dml.mathdoc.fr/item/1183731783} }
Fitch, Frederic B. A Definition of Negation in Extended Basic Logic. J. Symbolic Logic, Tome 19 (1954) no. 1, pp. 29-36. http://gdmltest.u-ga.fr/item/1183731783/