@article{Rybak2016some,
author={Rybak, A.L.},
title={Some peculiarities in longitude distribution of sunspot groups over last four eleven-year solar cycles},
journal={Solnechno-Zemnaya Fizika},
publisher={Institute of Solar-Terrestrial Physics SB RAS},
year={2016},
pages={22-28},
volume={2},
issue={2},
}