B. U. Pires, R. E. de Souza, M. Vedovello Filho, V. V. Degan, J. C. B. dos Santos, and C. A. M. Tubel, “Force degradation of different elastomeric chains and nickel titanium closed springs”, Braz. J. Oral Sci., vol. 10, no. 3, pp. 167–170, Nov. 2015.