These books are fairly accessible and touch on a lot of the same ideas you’d find in seminal works like Das Kapital

• Profit Pathology and Other Indecencies by Michael Parenti
• Understanding Marxism, Economics: Marxian Versus Neoclassical, and Understanding Socialism by Richard D. Wolff
• Super Imperialism and Finance Capitalism and Its Discontents by Michael Hudson
• Capitalism, Coronavirus and War by Radhika Desai