Tài liệu tham khảo WikiPedia: NGC 4650A http://nedwww.ipac.caltech.edu/ http://heritage.stsci.edu/1999/16/fast_facts.html //doi.org/10.1086%2F165077 https://ui.adsabs.harvard.edu/abs/1967ZA.....67..3... https://ui.adsabs.harvard.edu/abs/1987ApJ...314..4... https://arxiv.org/abs/astro-ph/0301391
