References
- McCallin, S. G. (1953) Retraction of maxillary teeth with removable appliances using intermaxillary traction or extra-oral traction, Transactions of the British Society for the Study of Orthodontics, 104–111.
- Usiskin, L. A. and Webb, W. G. (1972) Extra-oral anchorage for upper removable orthodontic appliances, British Dental Journal, 133, 140–145.