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Preston, C. B.; Evans, W. G.; Todres, J. I. (March 1997). "The relationship between ortho head posture and head posture measured during walking". American Journal of Orthodontics and Dentofacial Orthopedics. 111 (3): 283–287. doi:10.1016/s0889-5406(97)70186-0. ISSN0889-5406. PMID9082850.
Showfety, K. J.; Vig, P. S.; Matteson, S. (June 1983). "A simple method for taking natural-head-position cephalograms". American Journal of Orthodontics. 83 (6): 495–500. doi:10.1016/s0002-9416(83)90248-8. ISSN0002-9416. PMID6574706.
Cooke, Michael S.; Orth, D. (1990-06-01). "Five-year reproducibility of natural head posture: A longitudinal study". American Journal of Orthodontics and Dentofacial Orthopedics. 97 (6): 489–494. doi:10.1016/S0889-5406(05)80029-0. PMID2353678.
Lundström, A.; Lundström, F.; Lebret, L. M.; Moorrees, C. F. (April 1995). "Natural head position and natural head orientation: basic considerations in cephalometric analysis and research". European Journal of Orthodontics. 17 (2): 111–120. doi:10.1093/ejo/17.2.111. ISSN0141-5387. PMID7781719.
Preston, C. B.; Evans, W. G.; Todres, J. I. (March 1997). "The relationship between ortho head posture and head posture measured during walking". American Journal of Orthodontics and Dentofacial Orthopedics. 111 (3): 283–287. doi:10.1016/s0889-5406(97)70186-0. ISSN0889-5406. PMID9082850.
Showfety, K. J.; Vig, P. S.; Matteson, S. (June 1983). "A simple method for taking natural-head-position cephalograms". American Journal of Orthodontics. 83 (6): 495–500. doi:10.1016/s0002-9416(83)90248-8. ISSN0002-9416. PMID6574706.