D. Leiter, S. Robertson «Does the Principle of Equivalence Prevent Trapped Surfaces From being Formed in the General Relativistic Collapse Process?». Foundations of Physics Letters, 16, 2, 2003, pàg. 143. arXiv: astro-ph/0111421. DOI: 10.1023/A:1024170711427.(anglès)
R.E. Schild, D.J. Leiter, S.L. Robertson «Observations Supporting the Existence of an Intrinsic Magnetic Moment inside the Central Compact Object within the Quasar Q0957+561». Astronomical Journal, 132, 1, 2006, pàg. 420–432. arXiv: astro-ph/0505518. Bibcode: 2006AJ....132..420S. DOI: 10.1086/504898.(anglès)
A. Mitra «Non-occurrence of Trapped Surfaces and Black Holes in Spherical Gravitational Collapse: An Abridged Version». Foundations of Physics Letters, 13, 6, 2000, pàg. 543. arXiv: astro-ph/9910408. DOI: 10.1023/A:1007810414531.(anglès)
D. Leiter, S. Robertson «Does the Principle of Equivalence Prevent Trapped Surfaces From being Formed in the General Relativistic Collapse Process?». Foundations of Physics Letters, 16, 2, 2003, pàg. 143. arXiv: astro-ph/0111421. DOI: 10.1023/A:1024170711427.(anglès)
R.E. Schild, D.J. Leiter, S.L. Robertson «Observations Supporting the Existence of an Intrinsic Magnetic Moment inside the Central Compact Object within the Quasar Q0957+561». Astronomical Journal, 132, 1, 2006, pàg. 420–432. arXiv: astro-ph/0505518. Bibcode: 2006AJ....132..420S. DOI: 10.1086/504898.(anglès)
A. Mitra «Non-occurrence of Trapped Surfaces and Black Holes in Spherical Gravitational Collapse: An Abridged Version». Foundations of Physics Letters, 13, 6, 2000, pàg. 543. arXiv: astro-ph/9910408. DOI: 10.1023/A:1007810414531.(anglès)
R.E. Schild, D.J. Leiter, S.L. Robertson «Observations Supporting the Existence of an Intrinsic Magnetic Moment inside the Central Compact Object within the Quasar Q0957+561». Astronomical Journal, 132, 1, 2006, pàg. 420–432. arXiv: astro-ph/0505518. Bibcode: 2006AJ....132..420S. DOI: 10.1086/504898.(anglès)