%0 Journal Article
%A M. Breen
%T Covering in the set of principal ideals in the semigroup of binary relations.
%J Semigroup forum
%D 1994
%P 369-376
%V 48
%N 3
%I mathdoc
%U http://geodesic.mathdoc.fr/item/SF_1994__48_3_135325/
%F SF_1994__48_3_135325