Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J.
Houk, Nancy (1982), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 3, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1982mcts.book.....H.