Noyola, E. and Gebhardt, K. and Bergmann, M. (2008). "Gemini and Hubble Space Telescope Evidence for an Intermediate-Mass Black Hole in ω Centauri". The Astrophysical Journal676 (2): 1008–1015. doi:10.1086/529002. Bibcode: 2008ApJ...676.1008N.
Noyola, E. and Gebhardt, K. and Bergmann, M. (2008). "Gemini and Hubble Space Telescope Evidence for an Intermediate-Mass Black Hole in ω Centauri". The Astrophysical Journal676 (2): 1008–1015. doi:10.1086/529002. Bibcode: 2008ApJ...676.1008N.