@inproceedings{Grzelak:2020nG,
  author = "Grzelak, Grzegorz",
  title = "{Measurement of the $\psi(2S)$ and $J\psi$ cross section ratio in photoproduction with the ZEUS detector at HERA}",
  doi = "10.22323/1.364.0516",
  booktitle = "Proceedings of European Physical Society Conference on High Energy Physics {\textemdash} PoS(EPS-HEP2019)",
  year = 2020,
  volume = "364",
  pages = "516"
}