ARTYUKH Т., and SHEGINSKIY О. “esearch of irmness to ging of hoe ynthetic eather”. NTERNATIONAL CIENTIFIC-RACTICAL OURNAL OMMODITIES ND ARKETS, vol. 9, no. 1, June 2010, pp. 169-72, https://journals.knute.edu.ua/commodities-and-markets/article/view/1551.