Marani Barzani, Maryam, and Khairulmaini Bin Osman Salleh. “Surface Grain Size Variation Within Gravel Bars: A Case Study of the River Opava, Czech Republic”. Geografia Fisica E Dinamica Quaternaria, vol. 39, no. 1, June 2016, pp. 13-20, https://doi.org/10.4461/GFDQ.2016.39.2.