Tài liệu tham khảo WikiPedia: NGC_6397 http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=... //arxiv.org/abs/1001.4289 //arxiv.org/abs/1004.2255 //arxiv.org/abs/1008.2755 //doi.org/10.1088%2F0004-6256%2F140%2F6%2F1830 //doi.org/10.1111%2Fj.1365-2966.2010.16373.x //doi.org/10.1111%2Fj.1365-2966.2010.16813.x http://www.eso.org/outreach/press-rel/pr-2004/pr-2... http://server1.wikisky.org/starview?object=NGC+639... http://www.wikisky.org/?object=NGC+6397
