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Nemiroff, Robert; Bonnell, Jerry. Globular Star Cluster NGC 6752. Astronomy Picture of the Day. NASA. 5 July 2013 [20 August 2013]. (原始内容存档于2015-05-14).
Nemiroff, Robert; Bonnell, Jerry. Globular Star Cluster NGC 6752. Astronomy Picture of the Day. NASA. 5 July 2013 [20 August 2013]. (原始内容存档于2015-05-14).