Dorosz, S., Sawczuk, A., Biegus, A., Kowal, Z., & Seidel, W. (1980). Post-Yield Deflection of Elastic-Plastic Beams Under Uniformly Increasing Loads. Engineering Transactions, 29(2), 279-294. https://et3.ippt.pan.pl/index.php/et/article/view/2051