Harper, Graham M. (1992). “The outer atmospheres of the ‘hybrid’ bright giants: the chromospheres of α TrA (K4 II), ι AUR (K3 II), γ Aql (K3 II) and θ Her (K1 II)”. Monthly Notices of the Royal Astronomical Society256 (1): 37-64. Bibcode: 1992MNRAS.256...37H. doi:10.1093/mnras/256.1.37. ISSN0035-8711.
Harper, Graham M. (1992). “The outer atmospheres of the ‘hybrid’ bright giants: the chromospheres of α TrA (K4 II), ι AUR (K3 II), γ Aql (K3 II) and θ Her (K1 II)”. Monthly Notices of the Royal Astronomical Society256 (1): 37-64. Bibcode: 1992MNRAS.256...37H. doi:10.1093/mnras/256.1.37. ISSN0035-8711.
Harper, Graham M. (1992). “The outer atmospheres of the ‘hybrid’ bright giants: the chromospheres of α TrA (K4 II), ι AUR (K3 II), γ Aql (K3 II) and θ Her (K1 II)”. Monthly Notices of the Royal Astronomical Society256 (1): 37-64. Bibcode: 1992MNRAS.256...37H. doi:10.1093/mnras/256.1.37. ISSN0035-8711.