Tài liệu tham khảo WikiPedia: NGC_4414 http://nedwww.ipac.caltech.edu/ http://heritage.stsci.edu/1999/25/ //arxiv.org/abs/astro-ph/0406426 //doi.org/10.1086%2F306150 http://www.spacetelescope.org/images/html/opo9925a... https://ui.adsabs.harvard.edu/abs/1993A&A...280..4... https://ui.adsabs.harvard.edu/abs/1997A&A...318...... https://ui.adsabs.harvard.edu/abs/1998ApJ...505..2... https://ui.adsabs.harvard.edu/abs/1999AAS...194.82... https://apod.nasa.gov/apod/ap%C3%A0y3
