>>522250Technically the three volumes of "Theories of Surplus Value" compiled from his notes, first by Kautsky, and then independently again by the Marx and Engels institute in the USSR, are largely material that would have made it into the latter volumes of capital. Theories of Surplus Value is underrated because it goes into the history of political economy leading up to Marx. If you want a good taste of what it's like, here's Chapter 3 of Volume 1 regarding Marx's takes on Adam Smith.