1. The philosophy of the tooth positioning appliance;Kesling;Am J Orthod,1945
2. The vacuum formed dental contour appliance;Nahoum;N Y State Dent J,1964
3. Invisible retainers;Pontiz;Am J Orthod,1971
4. Invisible retainers;McNamara;J Clin Orthod,1985
5. Essix retainers: fabrication and supervision for permanent retention;Sheridan;J Clin Orthod,1993