Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373
De Medeiros, J. R.; Udry, S.; Burki, G.; Mayor, M. (2002), "A catalog of rotational and radial velocities for evolved stars. II. Ib supergiant stars", Astronomy and Astrophysics, 395: 97–98, Bibcode:2002A&A...395...97D, doi:10.1051/0004-6361:20021214.
Hunsch, M.; et al. (January 1998), "The ROSAT all-sky survey catalogue of optically bright late-type giants and supergiants", Astronomy and Astrophysics Supplement, 127 (2): 251–255, Bibcode:1998A&AS..127..251H, doi:10.1051/aas:1998347.
Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373
De Medeiros, J. R.; Udry, S.; Burki, G.; Mayor, M. (2002), "A catalog of rotational and radial velocities for evolved stars. II. Ib supergiant stars", Astronomy and Astrophysics, 395: 97–98, Bibcode:2002A&A...395...97D, doi:10.1051/0004-6361:20021214.
Hunsch, M.; et al. (January 1998), "The ROSAT all-sky survey catalogue of optically bright late-type giants and supergiants", Astronomy and Astrophysics Supplement, 127 (2): 251–255, Bibcode:1998A&AS..127..251H, doi:10.1051/aas:1998347.