%0 Journal Article %A Hammond %T A simple Proof of the Existence of Irreducible Invariants of Degrees 20 and 30 for the Binary Seventhic %J Mathematische Annalen %D 1890 %P 255-261 %V 36 %I mathdoc %U http://geodesic.mathdoc.fr/item/MAN_1890__36_157495/ %F MAN_1890__36_157495