[1] AN ATLAS OF STELLAR SPECTRA
WITH AN OUTLINE OF SPECTRAL CLASSIFICATION, W.W. Morgan, P.C. Keenan & E. Kellman, 1943, Chicago, Ill., The University of Chicago press
Table 5, William D. Vacca; Catharine D. Garmany & J. Michael Shull (April 1996). “The Lyman-Continuum Fluxes and Stellar Parameters of O and Early B-Type Stars”. 《Astrophysical Journal》 460: 914–931. Bibcode:1996ApJ...460..914V. doi:10.1086/177020.
Table 5, William D. Vacca; Catharine D. Garmany & J. Michael Shull (April 1996). “The Lyman-Continuum Fluxes and Stellar Parameters of O and Early B-Type Stars”. 《Astrophysical Journal》 460: 914–931. Bibcode:1996ApJ...460..914V. doi:10.1086/177020.