%0 Journal Article
%A Graham, R. L.
%T On Subtrees of Directed Graphs with No Path of Length Exceeding One
%J Canadian mathematical bulletin
%D 1970
%P 329-332
%V 13
%N 3
%U http://geodesic.mathdoc.fr/articles/10.4153/CMB-1970-063-1/
%R 10.4153/CMB-1970-063-1
%F 10_4153_CMB_1970_063_1