%0 Journal Article
%A S.A. Annin
%T Hierarchy of efficient generators of the symmetric inverse monoid.
%J Semigroup forum
%D 1997
%P 327-355
%V 54
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/SF_1997__54_2_135532/
%F SF_1997__54_2_135532