(en) R. O. Gray, M. G. Napier et L. I. Winkler, «The Physical Basis of Luminosity Classification in the Late A-, F-, and Early G-Type Stars. I. Precise Spectral Types for 372 Stars», The Astronomical Journal, vol.121, no4, , p.2148-2158 (DOI10.1086/319956, Bibcode2001AJ....121.2148G)
(en) R. O. Gray, M. G. Napier et L. I. Winkler, «The Physical Basis of Luminosity Classification in the Late A-, F-, and Early G-Type Stars. I. Precise Spectral Types for 372 Stars», The Astronomical Journal, vol.121, no4, , p.2148-2158 (DOI10.1086/319956, Bibcode2001AJ....121.2148G)