• NASA/JPL-Caltech - The Helix Nebula (NGC 7293)
  • SEDS - The Helix Nebula (NGC 7293)
  • NightSkyInfo – The Helix Nebula (NGC 7293)
  • Snopes - Helix Eye of God - Urban Legend
  • Helix Nebula (NGC 7293) at Constellation Guide