Bibcode:2007A&A...474..653V, arXiv:0708.1752 , doi:10.1051/0004-6361:20078357. Oja, T., Photoelectric photometry of stars near the north Galactic pole. II,
653V, S2CID 18759600, arXiv:0708.1752 , doi:10.1051/0004-6361:20078357 Oja, T., UBV photometry of stars whose positions are accurately known. III, Astronomy
Bibcode:2007A&A...474..653V, arXiv:0708.1752 , doi:10.1051/0004-6361:20078357 Oja, T., Photoelectric photometry of stars near the north Galactic pole. II,