M. A. Karim, M. Y. Salloom, and Y. N. Lafta, “Experimental Optimization of PLC-Integrated Multi-Loop PID Control for a Three-Level Electro-Hydraulic Elevator Using PSO and Cheetah Optimizer”, Eng. Technol. Appl. Sci. Res., vol. 16, no. 2, pp. 33836–33853, Apr. 2026.