@article{1183740200, author = {Bunder, M. W. and Seldin, Jonathan P.}, title = {Some Anomalies in Fitch's System $QD$}, journal = {J. Symbolic Logic}, volume = {43}, number = {1}, year = {1978}, pages = { 247-249}, language = {en}, url = {http://dml.mathdoc.fr/item/1183740200} }
Bunder, M. W.; Seldin, Jonathan P. Some Anomalies in Fitch's System $QD$. J. Symbolic Logic, Tome 43 (1978) no. 1, pp. 247-249. http://gdmltest.u-ga.fr/item/1183740200/