TY  - JOUR
AU  - Just, Winfried
TI  - Repercussions of a Problem of Erdős and Ulam on Density Ideals
JO  - Canadian journal of mathematics
PY  - 1990
SP  - 902
EP  - 914
VL  - 42
IS  - 5
UR  - http://geodesic.mathdoc.fr/articles/10.4153/CJM-1990-047-5/
DO  - 10.4153/CJM-1990-047-5
ID  - 10_4153_CJM_1990_047_5
ER  -