Das Kapital
Marx's magnum opus on political economy was "Das Kapital" ("Capital: A Critique of Political Economy") in three volumes, of which only the first volume was published in his lifetime (1867); the others were published by Friedrich Engels from Marx's notes. One of Marx's early works, "Critique of Political Economy", was mostly incorporated into "Das Kapital", especially the beginning of volume 1. Marx's notes made in preparation for writing "Das Kapital" were published in 1939 under the title "Grundrisse."