@article{bwmeta1.element.bwnjournal-article-fmv103i1p19bwm,
author = {J. Paris and G. Mills},
title = {Closure properties of countable non-standard integers},
journal = {Fundamenta Mathematicae},
volume = {103},
year = {1979},
pages = {205-215},
zbl = {0421.03051},
language = {en},
url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-fmv103i1p19bwm}
}
Paris, J.; Mills, G. Closure properties of countable non-standard integers. Fundamenta Mathematicae, Tome 103 (1979) pp. 205-215. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-fmv103i1p19bwm/