%0 Journal Article
%A Just, Winfried
%T Repercussions of a Problem of Erdős and Ulam on Density Ideals
%J Canadian journal of mathematics
%D 1990
%P 902-914
%V 42
%N 5
%U http://geodesic.mathdoc.fr/articles/10.4153/CJM-1990-047-5/
%R 10.4153/CJM-1990-047-5
%F 10_4153_CJM_1990_047_5