%0 Journal Article
%A Marek Wilhelm
%T Criteria of openness for relations
%J Fundamenta Mathematicae
%D 1981
%P 219-228
%V 114
%N 3
%I mathdoc
%U http://geodesic.mathdoc.fr/articles/10.4064/fm-114-3-219-228/
%R 10.4064/fm-114-3-219-228
%G en
%F 10_4064_fm_114_3_219_228