George Preston: The Chemically Peculiar Stars of the Upper Main Sequence. In: Annual Review of Astronomy and Astrophysics. Band 12, 1974, S, 257, doi:10.1146/annurev.aa.12.090174.001353.
Antonia C. Maury, Edward C. Pickering: Spectra of bright stars photographed with the 11-inch Draper Telescope as part of the Henry Draper Memorial. In: Annals of Harvard College Observatory. 1897, bibcode:1897AnHar..28....1M.