Lyubashits, V. Y., N. V. Razuvaev, A. Y. Mamychev, S. S. Shestopal, and B. V. I. “Signs of State and Their Historical Modifications”. Journal of History Culture and Art Research, vol. 7, no. 3, Sept. 2018, pp. 175-86, doi:10.7596/taksad.v7i3.1746.