@article{1183738447, author = {Cutland, Nigel}, title = {$\sum\_1$-Compactness and Ultraproducts}, journal = {J. Symbolic Logic}, volume = {37}, number = {1}, year = {1972}, pages = { 668-672}, language = {en}, url = {http://dml.mathdoc.fr/item/1183738447} }
Cutland, Nigel. $\sum_1$-Compactness and Ultraproducts. J. Symbolic Logic, Tome 37 (1972) no. 1, pp. 668-672. http://gdmltest.u-ga.fr/item/1183738447/