%0 Journal Article
%A Herrlich, Horst
%A Howard, Paul
%A Keremedis, Kyriakos
%T On preimages of ultrafilters in ZF
%J Commentationes Mathematicae Universitatis Carolinae
%D 2016
%P 241-252
%V 57
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/articles/10.14712/1213-7243.2015.159/
%R 10.14712/1213-7243.2015.159
%G en
%F 10_14712_1213_7243_2015_159