%0 Journal Article
%A F. HARARY
%T The Number of Functional Digraphs.
%J Mathematische Annalen
%D 1959
%P 203-210
%V 138
%I mathdoc
%U http://geodesic.mathdoc.fr/item/MAN_1959__138_160709/
%F MAN_1959__138_160709