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Hahn F, Kissling R, Weishaupt D, Boos N (July 2006). "The extremes of spinal motion: a kinematic study of a contortionist in an open-configuration magnetic resonance scanner: case report". Spine. 31 (16): E565–7. doi:10.1097/01.brs.0000225983.44327.b1. PMID16845345. S2CID23025533.
Hahn F, Kissling R, Weishaupt D, Boos N (July 2006). "The extremes of spinal motion: a kinematic study of a contortionist in an open-configuration magnetic resonance scanner: case report". Spine. 31 (16): E565–7. doi:10.1097/01.brs.0000225983.44327.b1. PMID16845345. S2CID23025533.