Yao, Si-sheng, and Nan-jing Huang. “A Class of Quasistatic Contact Problems for Viscoelastic Materials With Nonlocal Coulomb Friction and Time-Delay”. Mathematical Modelling and Analysis, vol. 19, no. 4, Sept. 2014, pp. 491-08, https://doi.org/10.3846/13926292.2014.956354.