Tài liệu tham khảo WikiPedia: NGC_7331 http://www.universetoday.com/2008/06/03/the-milky-... http://www.dsi-astronomie.de/NGC7331R.html http://nedwww.ipac.caltech.edu/ http://nedwww.ipac.caltech.edu/cgi-bin/nph-objsear... http://www.spitzer.caltech.edu/Media/releases/ssc2... http://antwrp.gsfc.nasa.gov/apod/ap040701.html http://ryutao.main.jp/english/st2k_ngc7331.html //arxiv.org/abs/1511.01907 //arxiv.org/abs/astro-ph/0210129 //doi.org/10.1086%2F127513
