↑"NED". NED–NASA/IPAC Extragalactic Database. Retrieved 17 July 2016.
↑R. W. Sinnott, editor (1988). The Complete New General Catalogue and Index Catalogue of Nebulae and StarClusters by J. L. E. Dreyer. Sky Publishing Corporation and Cambridge University Press. ISBN0-933346-51-4. {{cite book}}: |author= has generic name (help)
↑"VizieR Service". Strasbourg astronomical Data Center. Retrieved 17 July 2016.
