Nicholas J. McConnell et al. Two ten-billion-solar-mass black holes at the centres of giant elliptical galaxies. „Nature”. 480, s. 215–218, 2011-12-08. DOI: 10.1038/nature10636. arXiv:1112.1078. (ang.).
Courtney Seligman: NGC 4889. [w:] Celestial Atlas [on-line]. [dostęp 2015-05-25]. (ang.).
doi.org
Nicholas J. McConnell et al. Two ten-billion-solar-mass black holes at the centres of giant elliptical galaxies. „Nature”. 480, s. 215–218, 2011-12-08. DOI: 10.1038/nature10636. arXiv:1112.1078. (ang.).
haroldcorwin.net
Harold G. Corwin Jr.: NGC 4884 = NGC 4889, NGC 4889 = NGC 4884. [w:] Notes on the NGC objects, particularly those missing, misidentified, or otherwise unusual [on-line]. 2019-01-09. [dostęp 2019-03-03]. (ang.).
