Barbas, I. H., Kostritsa, S. O., Datsenko, V. N., Sultan, A. V., Dzychkovskyi, Y. M., & Krivchykov, A. Y. (2009). The study of dynamics and strength of hoppers (review article). Science and Transport Progress, (30), 27–32. https://doi.org/10.15802/stp2009/14600