@article{2018an,
author={, .. and , .. and , ..},
title={An approach to finding an integral characteristic of ionospheric and lightning activity from WWLLN observational data},
journal={Russian Journal of Earth Sciences},
publisher={Геофизический центр Российской Академии Наук},
year={2018},
pages={1-8},
volume={18},
issue={6},
}