Tài liệu tham khảo WikiPedia: NGC_6231 http://adsabs.harvard.edu/abs/1997A&A...317..532C http://www.docdb.net/show_object.php?id=ngc_6231 //arxiv.org/abs/1706.00017 //arxiv.org/abs/1807.02115 //doi.org/10.1007%2FBF02715061 //doi.org/10.3847%2F1538-3881%2Faa76e8 //doi.org/10.3847%2F1538-4357%2Faaef8c http://messier.seds.org/xtra/ngc/n6231.html http://server1.wikisky.org/starview?object=NGC+623... http://www.wikisky.org/?object=NGC+6231
