Rekola, R.; Richer, M.G.; McCall, Marshall L.; Valtonen, M.J.; Kotilainen, J.K.; Flynn, Chris (2005). «Distance to NGC 253 based on the planetary nebula luminosity function». Monthly Notices of the Royal Astronomical Society361 (1): 330–336. doi:10.1111/j.1365-2966.2005.09166.x. Bibcode: 2005MNRAS.361..330R.
Rekola, R.; Richer, M.G.; McCall, Marshall L.; Valtonen, M.J.; Kotilainen, J.K.; Flynn, Chris (2005). «Distance to NGC 253 based on the planetary nebula luminosity function». Monthly Notices of the Royal Astronomical Society361 (1): 330–336. doi:10.1111/j.1365-2966.2005.09166.x. Bibcode: 2005MNRAS.361..330R.
Dreyer, J. L. E. (1888). «A New General Catalogue of Nebulae and Clusters of Stars,being the Catalogue of the late Sir John F.W. Herschel, Bart., revised, corrected, and enlarged». Memoirs of the Royal Astronomical Society49: 1–237. Bibcode: 1888MmRAS..49....1D.
R. Barbon, E. Cappellaro, F. Ciatti, M. Turatto, C. T. Kowal (1984). «A revised supernova catalogue». Astronomy & Astrophysics Supplement Series58: 735–750. Bibcode: 1984A&AS...58..735B.