Gaia Collaboration; Brown, A. G. A.; Vallenari, A.; Prusti, T.; De Bruijne, J. H. J.; Mignard, F.; Drimmel, R.; Babusiaux, C.; et al. (2016), "Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties", Astronomy & Astrophysics, 595: A2, arXiv:1609.04172, Bibcode:2016A&A...595A...2G, doi:10.1051/0004-6361/201629512, S2CID1828208.
Gaia Collaboration; Brown, A. G. A.; Vallenari, A.; Prusti, T.; De Bruijne, J. H. J.; Mignard, F.; Drimmel, R.; Babusiaux, C.; et al. (2016), "Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties", Astronomy & Astrophysics, 595: A2, arXiv:1609.04172, Bibcode:2016A&A...595A...2G, doi:10.1051/0004-6361/201629512, S2CID1828208.
Keenan, P.; McNeil, R. (October 1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245–266, Bibcode:1989ApJS...71..245K, doi:10.1086/191373.
Gaia Collaboration; Brown, A. G. A.; Vallenari, A.; Prusti, T.; De Bruijne, J. H. J.; Mignard, F.; Drimmel, R.; Babusiaux, C.; et al. (2016), "Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties", Astronomy & Astrophysics, 595: A2, arXiv:1609.04172, Bibcode:2016A&A...595A...2G, doi:10.1051/0004-6361/201629512, S2CID1828208.
Keenan, P.; McNeil, R. (October 1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245–266, Bibcode:1989ApJS...71..245K, doi:10.1086/191373.
Gaia Collaboration; Brown, A. G. A.; Vallenari, A.; Prusti, T.; De Bruijne, J. H. J.; Mignard, F.; Drimmel, R.; Babusiaux, C.; et al. (2016), "Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties", Astronomy & Astrophysics, 595: A2, arXiv:1609.04172, Bibcode:2016A&A...595A...2G, doi:10.1051/0004-6361/201629512, S2CID1828208.