Lechman, M., and P.M. Lewiński. “Generalized Section Model for Analysis of Reinforced Concrete Chimney Weakened by Openings”. Engineering Transactions 49, no. 1 (March 31, 2001): 3–28. Accessed March 19, 2026. https://et.ippt.gov.pl/index.php/et/article/view/571.