@article{Yazev2021complexes,
author={Yazev, S.A. and Ulianova, M.M. and Isaeva, E.S.},
title={Complexes of activity on the Sun in solar cycle 21},
journal={Solar-Terrestrial Physics},
publisher={INFRA-M Academic Publishing LLC.},
year={2021},
pages={3-9},
volume={7},
issue={4},
}