Honglei Xu, Tingting Gu, Juan Zheng, and Kai Li. “LF Sky Wave Propagation Excited by a Horizontal Electric Dipole Towards Understanding of Its Radiation Mechanism”. Applied Computational Electromagnetics Society Journal (ACES), vol. 33, no. 06, July 2021, pp. 657-64, https://journals.riverpublishers.com/index.php/ACES/article/view/9125.