While the Nazis occupied France from 1940 to 1944, they were more lenient in their attacks on "degenerate art" in Paris than they were in the German-speaking nations under their military dictatorship. Matisse was allowed to exhibit along with other former Fauves and Cubists whom Hitler had initially claimed to despise, though without any Jewish artists, all of whose works had been purged from all French museums and galleries; any French artists exhibiting in France had to sign an oath assuring their "Aryan" status—including Matisse. He also worked as a graphic artist and produced black-and-white illustrations for several books and over one hundred original lithographs at the Mourlot Studios in Paris.