%0 Journal Article
%A N. Hindman
%T Strongly summable ultrafilters on N and small maximal subgroups of ßN.
%J Semigroup forum
%D 1991
%P 63-76
%V 42
%N 3
%I mathdoc
%U http://geodesic.mathdoc.fr/item/SF_1991__42_3_135065/
%F SF_1991__42_3_135065