S. Kumar, Supanna, et al. “Robust PID Controller Design for Rigid Uncertain Spacecraft Using Kharitonov Theorem and Vectored Particle Swarm Optimization”. International Journal of Engineering & Technology, vol. 7, no. 2.21, Apr. 2018, pp. 9-14, https://doi.org/10.14419/ijet.v7i2.21.11825.