Pickering, Edward Charles. Revised Harvard photometry : a catalogue of the positions, photometric magnitudes and spectra of 9110 stars, mainly of the magnitude 6.50, and brighter observed with the 2 and 4 inch meridian photometers. Annals of the Astronomical Observatory of Harvard College. 1908, 50. Bibcode:1908AnHar..50....1P.使用|accessdate=需要含有|url= (帮助)
Morgan, William Wilson; Keenan, Philip Childs; Kellman, Edith. An atlas of stellar spectra, with an outline of spectral classification. Chicago, Ill: The University of Chicago press. 1943. Bibcode:1943QB881.M6........使用|accessdate=需要含有|url= (帮助)
