Yoss, Kenneth M. (November 1961), "Spectral and Luminosity Classifications and Measurements of the Strength of Cyanogen Absorption for Late-Type Stars from Objective-Prism Spectra.", Astrophysical Journal, 134: 809, Bibcode:1961ApJ...134..809Y, doi:10.1086/147209
Yoss, Kenneth M. (November 1961), "Spectral and Luminosity Classifications and Measurements of the Strength of Cyanogen Absorption for Late-Type Stars from Objective-Prism Spectra.", Astrophysical Journal, 134: 809, Bibcode:1961ApJ...134..809Y, doi:10.1086/147209