Yakimchik, A. I. “On the Problem of Plotting Regional Analytical Approximations of Elements of the Elements of Anomalous Gravity Field”. Geofizicheskiy Zhurnal 31, no. 1 (February 1, 2009): 121–124. Accessed September 30, 2022. http://journals.uran.ua/geofizicheskiy/article/view/214054.