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Eggen, O. J. (1972). "Narrow-and broad-band photometry of red stars. VII. Luminosities and temperatures for halo-population red stars of high luminosity". The Astrophysical Journal. 172: 639. Bibcode:1972ApJ...172..639E. doi:10.1086/151383.
Celis, L. (1995). "Luminosity Attenuation and Distances of Red Giant Stars". The Astrophysical Journal Supplement Series. 98: 701. Bibcode:1995ApJS...98..701C. doi:10.1086/192175.