Hogg, Helen Battles Sawyer (outubro de 1965). «Harlow Shapley and Globular Clusters». Publications of the Astronomical Society of the Pacific. 77 (458): 336–46. Bibcode:1965PASP...77..336S. doi:10.1086/128229
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Hogg, Helen Battles Sawyer (outubro de 1965). «Harlow Shapley and Globular Clusters». Publications of the Astronomical Society of the Pacific. 77 (458): 336–46. Bibcode:1965PASP...77..336S. doi:10.1086/128229