@article{vanHoof:2831,
      author        = "van Hoof, P. A. M. and  Barlow, M. J. and  Exter, K. M.
                       and  Wesson, R. and  van de Steene, G. C. and  Groenewegen,
                       M. A. T.",
      title         = "{Herschel spectroscopy of planetary nebulae}",
      year          = "2011",
}