Piotto, Giampaolo (junho de 2009). Observations of multiple populations in star clusters. The Ages of Stars, Proceedings of the International Astronomical Union, IAU Symposium. 258. pp. 233–244. Bibcode:2009IAUS..258..233P. doi:10.1017/S1743921309031883
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Chaboyer, B. Globular Cluster Age Dating. Astrophysical Ages and Times Scales, ASP Conference Series. 245. pp. 162–172. Bibcode:2001ASPC..245..162C
Piotto, Giampaolo (junho de 2009). Observations of multiple populations in star clusters. The Ages of Stars, Proceedings of the International Astronomical Union, IAU Symposium. 258. pp. 233–244. Bibcode:2009IAUS..258..233P. doi:10.1017/S1743921309031883