Markova; Puls; Scuderi; Simon-Diaz; Herrero «Spectroscopic and physical parameters of Galactic O-type stars. I. Effects of rotation and spectral resolving power in the spectral classification of dwarfs and giants». The American Astronomical Society. arXiv: 1103.3357v1. Bibcode: 2011A&A...530A..11M. DOI: 10.1051/0004-6361/201015956.
Walborn; Fitzpatrick «Contemporary optical spectral classification of the OB stars – A digital atlas». Publications of the Astronomical Society of the Pacific. Bibcode: 1990PASP..102..379W. DOI: 10.1086/132646.
Walborn; Howarth; Lennon; Massey; Oey «A New Spectral Classification System for the Earliest O Stars: Definition of Type O2». The American Astronomical Society. Bibcode: 2002AJ....123.2754W. DOI: 10.1086/339831.
Markova; Puls; Scuderi; Simon-Diaz; Herrero «Spectroscopic and physical parameters of Galactic O-type stars. I. Effects of rotation and spectral resolving power in the spectral classification of dwarfs and giants». The American Astronomical Society. arXiv: 1103.3357v1. Bibcode: 2011A&A...530A..11M. DOI: 10.1051/0004-6361/201015956.
Walborn; Fitzpatrick «Contemporary optical spectral classification of the OB stars – A digital atlas». Publications of the Astronomical Society of the Pacific. Bibcode: 1990PASP..102..379W. DOI: 10.1086/132646.
Walborn; Howarth; Lennon; Massey; Oey «A New Spectral Classification System for the Earliest O Stars: Definition of Type O2». The American Astronomical Society. Bibcode: 2002AJ....123.2754W. DOI: 10.1086/339831.
Markova; Puls; Scuderi; Simon-Diaz; Herrero «Spectroscopic and physical parameters of Galactic O-type stars. I. Effects of rotation and spectral resolving power in the spectral classification of dwarfs and giants». The American Astronomical Society. arXiv: 1103.3357v1. Bibcode: 2011A&A...530A..11M. DOI: 10.1051/0004-6361/201015956.