Marxian economics refers to a heterodox school of economic thought. Its foundations can be traced back to the critique of classical political economy in the research by Karl Marx and Friedrich Engels. Marxian economics refers to several different theories and includes multiple schools of thought. Marx's magnum opus on political economy was "Das Kapital" in three volumes. Other notable works on economy include: "The Critique Of The Political Economy" as well as the books which preceded "Das Kapital", "Wage-Labor and Capital" and "Wages, Price and Profit". Contents: Wage-Labor and Capital Free Trade Wages, Price and Profit Capital A Contribution to The Critique Of The Political Economy