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Schödel, R.; Ott, T.; Genzel, R.; Hofmann, R.; Lehnert, M.; Eckart, A.; Mouawad, N.; Alexander, T. et al. (2002). “A star in a 15.2-year orbit around the supermassive black hole at the centre of the Milky Way”. Nature419 (6908): 694-696. doi:10.1038/nature01121. ISSN0028-0836.