brightness of the [Cepheid] variables and their periods." Kerri Malatesta (2010년 7월 16일). “Delta Cephei”. American Association of Variable Star Observers
“Hubble Space Telescope Fine Guidance Sensor Parallaxes of Galactic CepheidVariable Stars: Period-Luminosity Relations”. 《The Astronomical Journal》 133
“Hubble Space Telescope Fine Guidance Sensor Parallaxes of Galactic CepheidVariable Stars: Period-Luminosity Relations”. 《The Astronomical Journal》 133