@article{1093958157, author = {Soboci\'nski, Boles\l aw}, title = {A note on certain set-theoretical formulas.}, journal = {Notre Dame J. Formal Logic}, volume = {6}, number = {1}, year = {1965}, pages = { 157-160}, language = {en}, url = {http://dml.mathdoc.fr/item/1093958157} }
Sobociński, Bolesław. A note on certain set-theoretical formulas.. Notre Dame J. Formal Logic, Tome 6 (1965) no. 1, pp. 157-160. http://gdmltest.u-ga.fr/item/1093958157/