Tài liệu tham khảo WikiPedia: NGC_188 http://www.nightskyinfo.com/archive/ngc188/ http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=... //arxiv.org/abs/astro-ph/0502453 //doi.org/10.1051%2F0004-6361:20041113 //doi.org/10.1086%2F426340 http://iopscience.iop.org/article/10.1086/426340/p... http://messier.seds.org/xtra/ngc/n0188.html http://server1.wikisky.org/starview?object=NGC+188 http://www.wikisky.org/?object=NGC+188 http://www.wikisky.org/?object=NGC+188&img_source=...
