Mathematical modelling of traction resistance of the improved opener of grain seederGali S. Gumarov, Vladimir V. Konovalov, Amangeldy E. Sarsenov, Zhanna K. Kubasheva and Abelshaek A. RakhimovBIO Web Conf., 17 (2020) 00044DOI: https://doi.org/10.1051/bioconf/20201700044