Kev
One of the issues of Marxist econ is the lack of intermediate texts. After reading the volumes of Marx's capital and an introductory text, there is a gap in knowledge that allows someone to understand how to today's classical political economists apply Marxist system to the economy. Tsoulfidis and Tsalikis book imo opinion is the best intermediate text for learning the dual system interpretation of Marx's system. It starts from the basics of abstract labor and concrete labor, to introducing the reader to the transformation problem and the theory of real competition. It also includes empirical evidence to back up its claims which I appreciate.
I recommend reading this book before Shaikh's.
The book has some printing errors but nothing major. Only issue is a duplicate variable when comparing Marx's expanded reproduction schemes to the Keynesian harrod-domar growth model.
A great primer for understanding the basics of planning and addressing the economic issues of former socialist states.