Khalyavin, O.I., and L.Ya. Khalyavina. “Ballistic Gravimeter of the Poltava Gravimetric Observatory. History of Creation and Modernization”. Geofizicheskiy Zhurnal 48, no. 3 (June 24, 2026). Accessed June 27, 2026. https://journals.uran.ua/geofizicheskiy/article/view/356209.