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Grillmair, Carl J.; Faber, S. M.; Lauer, Tod R.; Baum, William A.; Lynds, Roger C.; O'Neil, Earl J. Jr.; Shaya, Edward J. (July 1994). "The nuclear regions of NGC 3311 and NGC 7768 imaged with the Hubble Space Telescope Planetary Camera". The Astronomical Journal. 108: 102. Bibcode:1994AJ....108..102G. doi:10.1086/117049. ISSN0004-6256.
McMahon, P. M.; van Gorkom, J. H.; Richter, O.-G.; Ferguson, H. C. (February 1992). "H I imaging of NGC 3312 and NGC 3314a - A foreground group to the Hydra cluster?". The Astronomical Journal. 103: 399. Bibcode:1992AJ....103..399M. doi:10.1086/116068. ISSN0004-6256.