Marie Curie signed ''Institut du Radium'', rare as from her own lab and not the more commonly seen Faculty of Sciences of Paris. Signed ''M. Curie'' as Director of the Laboratory, Curie approves the results of a radium experiment. Document in French is dated 20 July 1931, with handwritten annotations to the document likely completed in the hand of her assistant. Document measures 8.5'' x 12.25''. Chipping to top edge, overall in very good plus condition. Rare signed document concerning radiation by the twice-awarded Nobel Prize winner.