@article{Vaquero:2014,
  author  = "J. Vaquero and S. Gutiérrez-López and A. Szelecka",
  title   = "A note on the relationship between sunspot numbers and active days",
  journal = "Advances in Space Research",
  volume  = "Vol. 53",
  pages   = "1180--1183",
  year    = "2014",
  note    = "A. Szelecka - podwójna afiliacja",
}