Grygierek, Marcin. “Variability of Elastic Moduli of Unbound Layers of Road Pavements Subjected to Ravelling Strains Due to Mining”. Roads and Bridges - Drogi I Mosty, vol. 9, no. 2, Apr. 2010, pp. 17-30, https://rabdim.pl/index.php/rb/article/view/v9n2p17.