The following references are cited in this example problem:

Triches, M. Jr., Gerges, S. N. Y., & Jordon, R. (2004). Reduction of squeal noise from disc brake systems using constrained layer damping. Journal of the Brazilian Society of Mechanical Sciences and Engineering. 26, 340-343.

Allgaier, R., Gaul, L., Keiper, W., & Willner, K. (1999). Mode lock-in and friction modeling. Computational Methods in Contact Mechanics. 4, 35-47.

Schroth, R., Hoffmann, N., Swift, R. (2004, January). Mechanism of brake squeal from theory to experimentally measured mode coupling. In Proceedings of the 22nd International Modal Analysis Conference (IMAC XXII).