Which books explained Benedetto Croce's philosophy of the spirit?

Benedetto Croce’s "philosophy of the spirit" was developed in two distinct phases, each documented in specific works.

The Systematic Phase

In his earlier, systematic approach, Croce organized the spirit into four moments: aesthetic, logical, economic, and ethical. This structure is detailed in the following volumes:

• Estetica come scienza dell’espressione e linguistica generale (1902; Aesthetic As Science of Expression and General Linguistic)1
• Logica come scienza del concetto puro (1909; Logic As the Science of the Pure Concept)1
• Filosofia della pratica: economia ed etica (1909; Philosophy of the Practical: Economic and Ethic)1
• Teoria e storia della storiografia (1917; History: Its Theory and Practice)1

The Asystematic Phase

Croce later moved toward "absolute historicism," where the moments of the spirit are integrated into the flow of historical action. This evolution is signaled in:

• La storia come pensiero e come azione (1938; History As the Story of Liberty)1
• Filosofia, poesia, storia (1951; Philosophy, Poetry, History)1