%0 Journal Article
%A N. Hindman
%A D. Davenport
%T Subprincipal closed ideals in ßN.
%J Semigroup forum
%D 1987
%P 223-246
%V 36
%I mathdoc
%U http://geodesic.mathdoc.fr/item/SF_1987__36_134898/
%F SF_1987__36_134898