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X-ray diffraction patterns from a point source. (a) Zincblende (ZnS) crystal diffraction, recorded by P. Ewald; image from The Crystalline State by W.H. and W.L. Bragg; (b) cellulose fibres, oriented vertically [7]; (c) a lock of Mozart's hair, and (d) α-keratin diffraction pattern, from Mozart's hair (oriented obliquely) by William Astbury's colleague, Elwynn Beighton, in 1958.
