%0 Journal Article
%A H.H. JOHNSON
%T Classical Differential Invariants and Applications to Partial Differential Equations.
%J Mathematische Annalen
%D 1962
%P 308-329
%V 148
%I mathdoc
%U http://geodesic.mathdoc.fr/item/MAN_1962__148_161000/
%F MAN_1962__148_161000