Kalogera, Vassiliki & Baym, Gordon: The maxium mass of a neutron star. (Sivu L63, sitaatti 1: "The updated upper bound of 2.9 on the neutron star mass can be used to discriminate between neutron stars and black holes based on measurements of the mass function of the companion to the compact object." ja sivu L63 sitaatti 2: "In this way, nine black holes candidates have been identified so far. The lower limits of their masses lie in the range from 3.1 to 6 .") The Astrophysical Journal, Lokakuu 1996, 470. vsk, nro 1, s. L61–L64. IOPscience. Tutkimus. (PDF) Viitattu 19.2.2018. (englanniksi)