Phrenology (from Greek: φρήν phrēn, "mind" + λόγος logos, "knowledge"; "knowledge of the mind") is a hypothesis that locates individual mental faculties, such as reasoning or moral character, in particular regions or "organs" of the human brain, and proposes that such faculties are discoverable by cranioscopy (measurement of the skull), which is supposed by phrenologists to be a generally accurate outline of the brain mass. The theory was initially detailed by Franz Joseph Gall, a German neuroanatomist, during the early 19th century.
- Combe, George (1819), Essays on Phrenology: or, an Inquiry Into the Principles and Utility of the System of Drs. Gall and Spurzheim, and Into the Objections Made Against It, Edinburgh: Bell & Bradfute, https://archive.org/details/essaysonphrenolo00combiala
- Dewhurst, Henry William (1831), A Guide to Human and Comparative Phrenology: With Observations on the National Varieties of the Cranium, and a Description of Drs. Gall and Spurzheim's Method of Dissecting the Human Brain, London: W. Strange, https://archive.org/details/guidetohumancomp00dewh
- Manual of Phrenology: Being an Analytical Summary of the System of Doctor Gall, on the Faculties of Man and the Functions of the Brain, Philadelphia: Carey, Lea & Blanchard, 1835, https://archive.org/details/manualofphrenolo00philuoft
- The Psycograph, an automated phrenological measuring device