The article "Money and Monetary Systems: Selected Essays of Filippo Cesarano" explores various aspects of money, monetary systems, and monetary unions. The researchers discuss the demand for money, the new monetary economics, different monetary systems, and the viability of monetary unions. They also delve into the concept of optimum currency areas and provide a theoretical perspective on currency areas and equilibrium. The key findings include insights on financial innovation's impact on money demand, the relationship between legal restrictions and the dominance of money, and the considerations for providing the optimum quantity of money in different monetary systems.