Pichugin, S. F., V. P. Chichulin, and K. V. Chichulina. “SPATIAL STRUCTURES OF CLOSED PROFILES”. Academic journal Industrial Machine Building Civil Engineering 1, no. 48 (March 27, 2017): 138–143. Accessed February 16, 2026. https://ojs33.nupp.edu.ua/znp/article/view/787.