Goldsbury, Ryan; et al. (2010), "The ACS Survey of Galactic Globular Clusters. X. New Determinations of Centers for 65 Clusters", The Astronomical Journal, 140 (6): 1830–1837, Bibcode:2010AJ....140.1830G, doi:10.1088/0004-6256/140/6/1830.Parameter |month= yang tidak diketahui akan diabaikan (bantuan)
Hessels, J. W. T.; et al. (2007), "A 1.4 GHz Arecibo Survey for Pulsars in Globular Clusters", The Astrophysical Journal, 670 (1): 363–378, Bibcode:2007ApJ...670..363H, doi:10.1086/521780Parameter |month= yang tidak diketahui akan diabaikan (bantuan)
Forbes, Duncan A.; Bridges, Terry (2010), "Accreted versus in situ Milky Way globular clusters", Monthly Notices of the Royal Astronomical Society, 404 (3): 1203–1214, Bibcode:2010MNRAS.404.1203F, doi:10.1111/j.1365-2966.2010.16373.x.Parameter |month= yang tidak diketahui akan diabaikan (bantuan)
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Shapley, Harlow; Sawyer, Helen B. (1927), "A Classification of Globular Clusters", Harvard College Observatory Bulletin (849): 11–14, Bibcode:1927BHarO.849...11S.Parameter |month= yang tidak diketahui akan diabaikan (bantuan)
Goldsbury, Ryan; et al. (2010), "The ACS Survey of Galactic Globular Clusters. X. New Determinations of Centers for 65 Clusters", The Astronomical Journal, 140 (6): 1830–1837, Bibcode:2010AJ....140.1830G, doi:10.1088/0004-6256/140/6/1830.Parameter |month= yang tidak diketahui akan diabaikan (bantuan)
Hessels, J. W. T.; et al. (2007), "A 1.4 GHz Arecibo Survey for Pulsars in Globular Clusters", The Astrophysical Journal, 670 (1): 363–378, Bibcode:2007ApJ...670..363H, doi:10.1086/521780Parameter |month= yang tidak diketahui akan diabaikan (bantuan)
Forbes, Duncan A.; Bridges, Terry (2010), "Accreted versus in situ Milky Way globular clusters", Monthly Notices of the Royal Astronomical Society, 404 (3): 1203–1214, Bibcode:2010MNRAS.404.1203F, doi:10.1111/j.1365-2966.2010.16373.x.Parameter |month= yang tidak diketahui akan diabaikan (bantuan)
