Astronomy Pictures, "M99" (accessed 18 April 2010)
doi.org
dx.doi.org
Astronomical Journal, "Near-infrared surface photometry and morphology in virgo cluster spiral galaxy nuclear regions", Bernard J. Rauscher, April 1995, Bibcode: 1995AJ....109.1608R, doi:10.1086/117389
harvard.edu
adsabs.harvard.edu
Astronomical Journal, "Near-infrared surface photometry and morphology in virgo cluster spiral galaxy nuclear regions", Bernard J. Rauscher, April 1995, Bibcode: 1995AJ....109.1608R, doi:10.1086/117389
