@article{Hajduk:3968,
      author        = "Hajduk, M. and van Hoof, P. A. M. and Śniadkowska, K. and
                       Krankowski, A. and Błaszkiewicz, L. and Dąbrowski, B. and
                       Zijlstra, A. A.",
      title         = "{Radio observations of planetary nebulae: no evidence for
                       strong radial density gradients}",
      year          = "2018",
}