“Model of Plastic Strain of Material on a Free Surface of Cylindrical Patterns During Axial-Symmetric Compression. Part 2. Definition of Accumulated Strain and Intensity of Logarithmic Stains on the Basis of Different Approximations”. Visnyk of Vinnytsia Politechnical Institute, no. 3, Nov. 2010, pp. 99-102, https://visnyk.vntu.edu.ua/index.php/visnyk/article/view/1691.