Which major books did Herbert Spencer write?

Herbert Spencer was a prolific British philosopher and thinker of the Victorian era. His major writings include the following notable works:

• The Proper Sphere of Government (1843): A pamphlet arguing that the role of government should be limited to upholding natural rights.12
• Social Statics (1851): A work that outlined his views on social and economic laissez-faire.12
• The Principles of Psychology (1855): An early contribution to his broader philosophical system.2
• Education: Intellectual, Moral, and Physical (1861): A collection of essays that became a standard textbook in teacher-training colleges.12
• The Synthetic Philosophy (published 1855–1896): A comprehensive, multivolume system intended to unify knowledge across psychology, biology, sociology, and ethics. This series includes First Principles (1862) and The Principles of Sociology.12
• Descriptive Sociology (1873–1934): A series providing data on the social institutions of various societies.2