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Helmi, A; van Leeuwen, F; McMillan, P J; Massari, D; Antoja, T; Robin, A; Lindegren, L; Bastian, U (2018). Gaia Collaboration. "Gaia Data Release 2: Kinematics of globular clusters and dwarf galaxies around the Milky Way". Astronomy and Astrophysics. 616: A12. arXiv:1804.09381. Bibcode:2018A&A...616A..12G. doi:10.1051/0004-6361/201832698.