Shahinyan, S.G., and G.N. Kirakosyan. “ON THE OPTIMAL STABILIZATION OF A DOUBLE MATHEMATICAL PENDULUM HAVING A MOVABLE SUSPENSION CENTER”. Proceedings of the YSU A: Physical and Mathematical Sciences, vol. 45, no. 3 (226), Oct. 2011, pp. 31-39, doi:10.46991/PYSU:A/2011.45.3.031.