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Robert Heinlein wrote a novel (one of his earlier novels, I believe) in which China had invaded the USA and the Americans, in order to combat and confuse their invaders, developed a weapon (tool?) which could change matter into just about anything. I am looking for the title of that book and I apologize for the short summary (which may be only partially accurate -- I am old and my memory is fading). But I'd like to get a copy of that old book. Any help would be greatly appreciated.