@article{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",
  journal = "PoS",
  year = 2020,
  volume = "EPS-HEP2019",
  pages = "516"
}