Marx Brothers appeared, sometimes with Chico and Zeppo caricatured, in cartoons starring Mickey Mouse, Flip the Frog and others. In the "Airwolf" episode 'Condemned', four anti-virus formulae for a deadly plague were named after the four Marx Brothers. In "All in the Family", Rob Reiner often did imitations of Groucho, and Sally Struthers dressed as Harpo in one episode in which she (as Gloria Stivic) and Rob (as Mike Stivic) were going to a Marx Brothers film festival, with Reiner dressing as Groucho. Gabe Kaplan did many Groucho imitations on his sit-com "Welcome Back, Kotter" and Robert Hegyes sometimes imitated both Chico
Karl Marx and the Close of His System labour value, he argues that the basic error in Marx's system resulted from a self-contradiction of Marx's law of value, namely how the rate of profit and the prices of production of the third volume of Marx's "Capital" contradict Marx's theory of value in the first volume. He maintains that since the law of value is not directly controlling in capitalist production, the theory of value must be abandoned. Bawerk also attacks Marx for downplaying the influence of supply and demand in determining permanent price, and for deliberate ambiguity with such concepts. "Karl Marx and the Close of His System"