Eggen, O. J. (April 1968), "Photometric evidence for the existence of a delta Lyrae cluster", Astrophysical Journal, 152: 77, Bibcode:1968ApJ...152...77E, doi:10.1086/149525.
Eggen, O. J. (April 1968), "Photometric evidence for the existence of a delta Lyrae cluster", Astrophysical Journal, 152: 77, Bibcode:1968ApJ...152...77E, doi:10.1086/149525.