Lefèvre, L.; Marchenko, S. V.; Moffat, A. F. J.; Acker, A. (November 2009), "A systematic study of variability among OB-stars based on HIPPARCOS photometry", Astronomy & Astrophysics, 507 (2): 1141–1201, Bibcode:2009A&A...507.1141L, doi:10.1051/0004-6361/200912304.
Lefèvre, L.; Marchenko, S. V.; Moffat, A. F. J.; Acker, A. (November 2009), "A systematic study of variability among OB-stars based on HIPPARCOS photometry", Astronomy & Astrophysics, 507 (2): 1141–1201, Bibcode:2009A&A...507.1141L, doi:10.1051/0004-6361/200912304.
Houk, Nancy (1979), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 3, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode:1982mcts.book.....H.