@article{Babiarz:2020Ma,
  author = "Babiarz, Izabela  and  Goncalves, Victor P  and  Pasechnik, Roman  and  Schaefer, Wolfgang  and  Szczurek, Antoni",
  title = "{The ${\gamma^* \gamma^* \to \eta_c (1S,2S)}$ transition form factors for two spacelike photons}",
  doi = "10.22323/1.364.0467",
  journal = "PoS",
  year = 2020,
  volume = "EPS-HEP2019",
  pages = "467"
}