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Abt, Helmut A.; et al. (October 1990), "The Frequency and Formation Mechanism of B2--B5 Main-Sequence Binaries", Astrophysical Journal Supplement, 74: 551, Bibcode:1990ApJS...74..551A, doi:10.1086/191508.
Adelman, Saul J. (June 1998), "Elemental abundance analyses with DAO spectrograms - XIX. The superficially normal B stars zeta Draconis, epsilon Lyrae, 8 Cygni and 22 Cygni", Monthly Notices of the Royal Astronomical Society, 296 (4): 856–862, Bibcode:1998MNRAS.296..856A, doi:10.1046/j.1365-8711.1998.01426.x.