(EN) J. F. C. Santos Jr, A. E. Piatti, Ages and metallicities of star clusters: New calibrations and diagnostic diagrams from visible integrated spectra (abstract), in Astronomy and Astrophysics, vol. 428, n. 1, 23 novembre 2004, DOI:10.1051/0004-6361:20041560.
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(EN) J. F. C. Santos Jr, A. E. Piatti, Ages and metallicities of star clusters: New calibrations and diagnostic diagrams from visible integrated spectra (abstract), in Astronomy and Astrophysics, vol. 428, n. 1, 23 novembre 2004, DOI:10.1051/0004-6361:20041560.