Keenan, P.C. (1993). «Revised MK Spectral Classification of the Red Carbon Stars». Publications of the Astronomical Society of the Pacific105: 905. doi:10.1086/133252. Bibcode: 1993PASP..105..905K.
Tanaka, M. (2007). «Near-Infrared Spectra of 29 Carbon Stars: Simple Estimates of Effective Temperature». Publications of the Astronomical Society of Japan59: 939. doi:10.1093/pasj/59.5.939. Bibcode: 2007PASJ...59..939T.
Keenan, P.C. (1993). «Revised MK Spectral Classification of the Red Carbon Stars». Publications of the Astronomical Society of the Pacific105: 905. doi:10.1086/133252. Bibcode: 1993PASP..105..905K.
Tanaka, M. (2007). «Near-Infrared Spectra of 29 Carbon Stars: Simple Estimates of Effective Temperature». Publications of the Astronomical Society of Japan59: 939. doi:10.1093/pasj/59.5.939. Bibcode: 2007PASJ...59..939T.