(1)
Hambardzumyan, S. R. ON THE STABILITY BY ACTING FORCE WITH PAIR IMAGINING ROOTS FOR THE SECOND ORDER SYSTEM. Proc. YSU A: Phys. Math. Sci. 2003, 37 (3 (202), 50-56. https://doi.org/10.46991/PYSUA.2003.37.3.050.