Mierzejewska, Magdalena, and Stanisław Pisarczyk. “Investigation of Shear Strength of Clay-Gravel, Coarse-Grained Soils”. Roads and Bridges - Drogi I Mosty, vol. 7, no. 3, Apr. 2008, pp. 35-53, https://rabdim.pl/index.php/rb/article/view/v7n3p35.