Philip Massey, Kathleen DeGioia-Eastwood, ja Elizabeth Waterhouse: The Progenitor Masses of Wolf-Rayet Stars and Luminous Blue Variables Determined from Cluster Turnoffs. II. Results from 12 Galactic Clusters and OB Associations. The Astronomical Journal, 2001, 121. vsk, s. 1050–1070. doi:10.1086/318769(englanniksi)
