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esa.int
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harvard.edu
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P. T. de Zeeuw, R. Hoogerwerf, J. H. J. de Bruijne, A. G. A. Brown, A. Blaauw. A HIPPARCOS Census of the Nearby OB Associations. The Astronomical Journal. 1999, 117 (1): 354–399 [2008-02-16]. (原始内容存档于2008-02-02).
OB Associations. The GAIA Study Report: Executive Summary and Science Section. 2000-04-06 [2006-06-08]. (原始内容存档于2003-08-04) (英语).
P. T. de Zeeuw, R. Hoogerwerf, J. H. J. de Bruijne, A. G. A. Brown, A. Blaauw. A HIPPARCOS Census of the Nearby OB Associations. The Astronomical Journal. 1999, 117 (1): 354–399 [2008-02-16]. (原始内容存档于2008-02-02).
B. Elmegreen, Y. N. Efremov. The Formation of Star Clusters. American Scientist. 1999, 86 (3): 264 [2006-08-23]. (原始内容存档于2005-03-23).