%0 Journal Article
%A Erdös, P.
%T On a Problem of Groübaum
%J Canadian mathematical bulletin
%D 1972
%P 23-25
%V 15
%N 1
%U http://geodesic.mathdoc.fr/articles/10.4153/CMB-1972-005-4/
%R 10.4153/CMB-1972-005-4
%F 10_4153_CMB_1972_005_4