Kollatschny, W.; Fricke, K. J.; Hellwig, J. (1986), "Double Nucleus Galaxies", in Giuricin, G.; Mardirossian, F.; Mezzetti, M.; Ramella, M. (eds.), Structure and Evolution of Active Galactic Nuclei: International Meeting Held in Trieste, Italy, April 10–13, 1985, vol.121, Dordrecht: Springer Netherlands, pp.605–609, Bibcode:1986ASSL..121..605K, doi:10.1007/978-94-009-4562-3_58, ISBN978-94-009-4562-3, retrieved 2024-04-30
Kollatschny, W.; Fricke, K. J.; Hellwig, J. (1986), "Double Nucleus Galaxies", in Giuricin, G.; Mardirossian, F.; Mezzetti, M.; Ramella, M. (eds.), Structure and Evolution of Active Galactic Nuclei: International Meeting Held in Trieste, Italy, April 10–13, 1985, vol.121, Dordrecht: Springer Netherlands, pp.605–609, Bibcode:1986ASSL..121..605K, doi:10.1007/978-94-009-4562-3_58, ISBN978-94-009-4562-3, retrieved 2024-04-30