Nowak, J., W. Przystupa, and A. Krawczuk. “Uncertainty of Measurement of Bulk and Shaken Density of Pulgran and Salmag”. Agricultural Engineering , Vol. 24, no. 3, Sept. 2020, pp. 73-81, https://agriceng.ptir.org/index.php/AgricEng/article/view/253.