@article{1183733110, author = {Fitch, Frederic B.}, title = {An Extensional Variety of Extended Basic Logic}, journal = {J. Symbolic Logic}, volume = {23}, number = {1}, year = {1958}, pages = { 13-21}, language = {en}, url = {http://dml.mathdoc.fr/item/1183733110} }
Fitch, Frederic B. An Extensional Variety of Extended Basic Logic. J. Symbolic Logic, Tome 23 (1958) no. 1, pp. 13-21. http://gdmltest.u-ga.fr/item/1183733110/